Sample1
(1) Calculate, paying attention to the parentheses
| (49 + 10) + 4 = | (60 + 2) + 6 = | (82 + 10) + 10 = | 9 + (70 + 8) = |
| 10 + (36 + 20) = | 5 + (51 + 7) = | (39 + 18) + 6 = | 9 + (49 + 10) = |
(2) Calculate:
| 46 + = 61 | + 59 = 90 | 63 − = 26 | − 11 = 66 |
| 26 + = 83 | + 55 = 83 | 92 − = 36 | − 68 = 23 |
| 57 + = 91 | + 73 = 97 | 79 − = 31 | − 56 = 30 |
(3) Subtract and check by adding
| 95 − 30 = 65 | since 65 + 30 = 95 | 71 − 20 = | since + 20 = |
| 80 − 40 = | since + 40 = | 92 − 30 = | since + 30 = |
| 57 − 30 = | since + 30 = | 43 − 20 = | since + 20 = |
| 75 − 20 = | since + 20 = | 42 − 30 = | since + 30 = |