# Adding and Subtracting to 100 *30 minutes, 3 stages* You are getting better at adding and subtracting two-digit numbers. This homework helps you practice making tens and using doubles to solve problems within 100 ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844), [Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)). ## Stage 1: Warm-up (8 min) Warm up your brain with number facts. Write the answers: 1. 6 + 4 =? 2. 7 + 3 =? 3. 5 + 5 =? 4. 10 − 6 =? 5. 10 − 4 =? Now use a double to help you. Doubles are facts like 4 + 4 or 6 + 6 ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)). 6. 6 + 7 =? (Hint: think of 6 + 6, then add 1 more.) 7. 8 + 9 =? (Hint: think of 8 + 8, then add 1 more.) Draw a quick tens frame or use your fingers if you get stuck. ## Stage 2: Practice (15 min) Now try two-digit problems. Use the "make a ten" strategy: break a number apart to reach a friendly ten first ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)). Solve these: 1. 27 + 5 =? 2. 34 + 8 =? 3. 46 + 9 =? 4. 63 − 7 =? 5. 52 − 6 =? For each problem, show your thinking. For example, for 27 + 5, you could write: 27 + 3 = 30, then 30 + 2 = 32. Now try one with three addends. Remember, you can add numbers in any order and get the same sum ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29846), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)). 6. 20 + 30 + 10 =? 7. 15 + 5 + 40 =? Check one of your answers using the opposite operation. If you added, subtract to check. If you subtracted, add to check ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)). 8. Pick problem 4 above. Write a subtraction fact and use addition to check it worked. ## Stage 3: Word problems (7 min) Solve these problems about things you can count or measure ([Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)). 1. Mia has 38 stickers. Her friend gives her 25 more. How many stickers does Mia have now? 2. A ribbon is 84 centimetres long. A piece 19 centimetres long is cut off. How long is the ribbon now? 3. There is a missing number in this sum: 45 +? = 100. Find the missing number ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)). Show your work for each problem, not just the answer. ## Self-check 1. What strategy did you use most today: making a ten, or using doubles? 2. Pick one problem from Stage 2. Explain how you checked your answer using the inverse operation. 3. Can you think of another way to make 45 + 55 = 100? Write it down. --- *AILI student homework · language en · model claude-sonnet-5 · generated 2026-09-17 · id 22a393df-02f4-4e7c-a188-ea6f7f89e566* ### Sources - node:n1: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29843) - node:n2: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844) - node:n3: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29846) - node:n4: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848) - node:n5: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847) - node:n6: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850) - node:n7: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852) - node:n8: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851) - node:n9: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852) - node:n10: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850) - node:n11: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848) - node:n12: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844) - node:n13: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847) - resource:r1: Resources › type#assessment, type#lessonplan › MAT2 (https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/0NK9kueDjkiTuLghkTw7gA) - resource:r2: Resources › type#assessment, type#lessonplan › MAT2 (https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/UBR9NyaKR06rLqRstqVy0w) - resource:r3: Resources › type#assessment, type#lessonplan › MAT2 (https://goa-cc-uat-aili-app-001.azurewebsites.net/library/resource/N0Zgv8CvBkS45pSOaAiBzA)