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Reasonableness with Fractions and Decimals. For Addition. Find what whole numbers the first decimal or fraction would be between. Write the two numbers down. Find what whole numbers the second decimal or fraction would be between. Write the two numbers down below the other two.
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For Addition • Find what whole numbers the first decimal or fraction would be between. • Write the two numbers down.
Find what whole numbers the second decimal or fraction would be between. • Write the two numbers down below the other two.
5. Add the pairs of whole numbers. 6. Work the “real” problem.
7. Make sure your answer is BETWEEN the “answer range” answers. If it IS NOT BETWEEN, your answer is wrong!
0 1 2 3 4 What whole numbers is 2 between on a number line? 2 + 3
0 1 2 3 4 2 3 2 + 3
0 1 2 3 4 What whole numbers is 3 between on a number line? 2 + 3 2 3
0 1 2 3 4 3 4 2 + 3 2 3
0 1 2 3 4 2 + 3 2 3 4 + 3 + 7 5
x 4 1 x 4 x 3 1 x 3 8 2 + 3 9 17 = 1
0 1 2 3 4 6 8 1 567 2 + 3 Is it in our "answer range"? O 2 3 4 + 3 + 7 5 1
0 1 2 3 4 5 6 78 1 What did I do wrong? 2 + 3 2 3 4 + 3 + 7 5 1
0 1 2 3 4 5 6 78 9 1 2 + 3 2 3 4 + 3 + 7 5 5+
0 1 2 3 4 5 6 78 9 6 2 + 3 2 3 4 + 3 + 7 5 6
0 1 2 3 4 6 8 9 6 567 2 + 3 Is it in our "answer range"? ü 2 3 4 + 3 + 7 5 6
0 1 2 3 4 5 6 7 8 9 What whole numbers is 4 between on a number line? 4 + 3
0 1 2 3 4 5 6 7 8 9 4 5 4 + 3
0 1 2 3 4 5 6 7 8 9 What whole numbers is 3 between on a number line? 4 + 3 4 5
0 1 2 3 4 5 6 7 8 9 3 4 4 + 3 4 5
0 1 2 3 4 5 6 7 8 9 4 + 3 4 5 4 + 3 + 9 7
x 2 1 x 2 4 + 3 2 5 = 1
0 1 2 3 4 5 6 8 1 79 4 + 3 Is it in our "answer range"? O 4 5 4 + 3 + 9 7 1
0 1 2 3 4 5 6 78 9 8 4 + 3 4 5 4 + 3 + 9 7 8
0 1 2 3 4 5 6 8 8 79 4 + 3 Is it in our "answer range"? ü 4 5 4 + 3 + 9 7 8
0 1 2 3 4 5 6 7 8 9 What whole numbers is .075 between on a number line? .075 + 5.2
0 1 2 3 4 5 6 7 8 9 0 1 .075 + 5.2
0 1 2 3 4 5 6 7 8 9 What whole numbers is 5.2 between on a number line? .075 + 5.2 0 1
0 1 2 3 4 5 6 7 8 9 5 6 .075 + 5.2 0 1
0 1 2 3 4 5 6 7 8 9 0 1 6 + 5 + .075 + 5.2 7 5
0 1 2 3 4 6 8 9 57 O Is it in our "answer range"? 0 1 6 + 5 + .075 + 5.2= .127 .127 7 5
0 1 2 3 4 6 8 9 What did I do wrong? 57 .075 + 5.2=1.27 0 1 6 + 5 + 7 5
0 1 2 3 4 6 8 9 57 + .075 +5.200 Is it in our "answer range"? ü 0 1 6 + 5 + 5.275 5.275 7 5
0 1 2 3 4 5 6 7 8 9 What whole numbers is 1.375 between on a number line? 1.375 + 4
0 1 2 3 4 5 6 7 8 9 1 2 1.375 + 4
4 is a whole number. Just use 4 both times. 1.375 + 4 1 2
0 1 2 3 4 5 6 7 8 9 4 4 1.375 + 4 1 2
0 1 2 3 4 5 6 7 8 9 1.375 + 4 1 2 4 + 4 + 6 5
0 1 2 3 4 78 9 56 1.375 + 4= O Is it in our "answer range"? 1 2 4 + 4 + 6 5 1.379 1.379
0 1 2 3 4 78 9 What did I do wrong? 56 1.375 + 4=1.379 1 2 4 + 4 + 6 5
0 1 2 3 4 78 9 56 +1.375 +4.000 Is it in our "answer range"? ü 1 2 4 + 4 + 5.375 5.375 6 5
For Subtraction • Follow steps 1 – 3 from addition. • Switch the 2nd numbers before you write them down.
Subtract. If you get the same answer, instead of an “answer range”, you forgot to SWITCH the set of numbers.
4. Work the “real” problem. 5. Make sure your answer is BETWEEN the “answer range” answers.
0 1 2 3 4 5 6 7 8 What whole numbers is 3 between on a number line? 3 - 1
0 1 2 3 4 6 8 3 4 3 - 1
What whole numbers is 1 between on a number line? 0 1 2 3 4 5 6 7 8 3 - 1 3 4
0 1 2 3 4 5 6 7 8 1 2 3 - 1 3 4
0 1 2 3 4 5 6 7 8 If you get the same answer, instead of an “answer range”, you forgot to SWITCH the set of numbers. 3 - 1 3 4 2 - 1 - 2 2