Sample1
(1) Calculate, paying attention to the parentheses
| (44 + 10) + 2 = | (69 + 4) + 10 = | (87 + 6) + 6 = | 8 + (79 + 10) = |
| 10 + (31 + 10) = | 7 + (52 + 8) = | (37 + 20) + 6 = | 7 + (45 + 6) = |
(2) Calculate:
| 45 + = 66 | + 53 = 90 | 68 − = 27 | − 16 = 61 |
| 25 + = 86 | + 56 = 85 | 93 − = 40 | − 63 = 24 |
| 51 + = 91 | + 75 = 97 | 73 − = 31 | − 59 = 40 |
(3) Subtract and check by adding
| 86 − 40 = 46 | since 46 + 40 = 86 | 74 − 20 = | since + 20 = |
| 87 − 20 = | since + 20 = | 92 − 40 = | since + 40 = |
| 60 − 30 = | since + 30 = | 49 − 30 = | since + 30 = |
| 72 − 20 = | since + 20 = | 74 − 20 = | since + 20 = |
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