运用加法交换律或加法结合律使计算简便
$30 + 50 + 50 =$$+ ($$+ $$) =$
$34 + 81 + 19 =$$+ ($$+ $$) =$
$35 + 61 + 39 =$$+ ($$+ $$) =$
$85 + 84 + 16 =$$+ ($$+ $$) =$
$42 + 104 + 58 =$$+ ($$+ $$) =$
$63 + 25 + 37 = ($$+ $$) + $$=$
$236 + 106 + 94 = ($$+ $$) + $$=$
$543 + 242 + 158 = ($$+ $$) + $$=$
$170 + 29 + 30 = ($$+ $$) + $$=$
$45 + 99 + 155 = ($$+ $$) + $$=$
$38 + 50 + 162 =$$+ ($$+ $$) =$
$69 + 60 + 40 =$$+ ($$+ $$) =$
$27 + 73 + 26 =$$+ ($$+ $$) =$
$32 + 20 + 80 =$$+ ($$+ $$) =$
$28 + 65 + 35 =$$+ ($$+ $$) =$
$43 + 34 + 66 =$$+ ($$+ $$) =$
$75 + 54 + 46 =$$+ ($$+ $$) =$
$133 + 54 + 67 =$$+ ($$+ $$) =$

$30 + 50 + 50 = 30 + (50 + 50) = 130$
$34 + 81 + 19 = 34 + (81 + 19) = 134$
$35 + 61 + 39 = 35 + (61 + 39) = 135$
$85 + 84 + 16 = 85 + (84 + 16) = 185$
$42 + 104 + 58 = 104 + (42 + 58) = 204$
$63 + 25 + 37 = (63 + 37) + 25 = 125$
$236 + 106 + 94 = (106 + 94) + 236 = 436$
$543 + 242 + 158 = (242 + 158) + 543 = 943$
$170 + 29 + 30 = (170 + 30) + 29 = 229$
$45 + 99 + 155 = (45 + 155) + 99 = 299$
$38 + 50 + 162 = 50 + (38 + 162) = 250$
$69 + 60 + 40 = 69 + (60 + 40) = 169$
$27 + 73 + 26 = 26 + (27 + 73) = 126$
$32 + 20 + 80 = 32 + (20 + 80) = 132$
$28 + 65 + 35 = 28 + (65 + 35) = 128$
$43 + 34 + 66 = 43 + (34 + 66) = 143$
$75 + 54 + 46 = 75 + (54 + 46) = 175$
$133 + 54 + 67 = 54 + (133 + 67) = 254$

在（）里填上合适的数
$37 + ($$) = 100$
$56 + ($$) = 100$
$28 + ($$) = 100$
$45 + ($$) = 100$
$81 + ($$) = 100$
$68 + ($$) = 100$
$($$) + 23 = 200$
$($$) + 57 = 200$
$($$) + 91 = 200$
$($$) + 119 = 200$
$($$) + 179 = 200$
$($$) + 92 = 200$
$($$) + 165 = 200$
$70 + 80 = 500 - ($$)$
$100 - 35 = ($$) + 5$
$200 - 136 = ($$) - 6$
$200 + 500 = 1000 - ($$)$
$320 - 20 = 229 + ($$)$
时间（）

1. $37 + (63) = 100$；
2. $56 + (44) = 100$；
3. $28 + (72) = 100$；
4. $45 + (55) = 100$；
5. $81 + (19) = 100$；
6. $68 + (32) = 100$；
7. $(177) + 23 = 200$；
8. $(143) + 57 = 200$；
9. $(109) + 91 = 200$；
10. $(81) + 119 = 200$；
11. $(21) + 179 = 200$；
12. $(108) + 92 = 200$；
13. $(35) + 165 = 200$；
14. $70 + 80 = 500 - (350)$；
15. $100 - 35 = (60) + 5$；
16. $200 - 136 = (70)- 6$（或$70$可写成$64+6$的计算结果$70$）；
直接填结果：$200 - 136 = (70) - 6$；
17. $200 + 500 = 1000 - (300)$；
18. $320 - 20 = 229 + (71)$；
19.时间（此处题目不完整，无法作答）。

3
怎么简便就怎么算
$38 + 25 + 62 = (38 + 62) + 25 = 125$
$64 + 36 + 147 =$
$239 + 48 + 61 =$
$156 + 274 + 126 =$
$175 + 27 + 225 =$
$119 + 81 + 264 =$
$81 + 267 + 33 =$
$128 + 72 + 45 =$
$69 + 84 + 31 =$
$76 + 58 + 124 =$
$251 + 67 + 49 =$
$87 + 113 + 25 =$
$94 + 38 + 106 + 62 =$
$23 + 48 + 52 + 77 =$
$58 + 39 + 61 + 42 =$
$73 + 49 + 51 + 27 =$
$45 + 48 + 155 + 52 =$
$(174 + 293) + 126 =$

$64 + 36 + 147$
$=(64 + 36)+147$
$=100 + 147$
$=247$
$239 + 48 + 61$
$=(239+61)+48$
$=300 + 48$
$=348$
$156 + 274 + 126$
$=156+(274 + 126)$
$=156 + 400$
$=556$
$175 + 27 + 225$
$=(175+225)+27$
$=400 + 27$
$=427$
$119 + 81 + 264$
$=(119+81)+264$
$=200 + 264$
$=464$
$81 + 267 + 33$
$=81+(267+33)$
$=81 + 300$
$=381$
$128 + 72 + 45$
$=(128+72)+45$
$=200 + 45$
$=245$
$69 + 84 + 31$
$=(69+31)+84$
$=100 + 84$
$=184$
$76 + 58 + 124$
$=(76+124)+58$
$=200 + 58$
$=258$
$251 + 67 + 49$
$=(251+49)+67$
$=300 + 67$
$=367$
$87 + 113 + 25$
$=(87+113)+25$
$=200 + 25$
$=225$
$94 + 38 + 106 + 62$
$=(94+106)+(38+62)$
$=200+100$
$=300$
$23 + 48 + 52 + 77$
$=(23+77)+(48+52)$
$=100 + 100$
$=200$
$58 + 39 + 61 + 42$
$=(58+42)+(39+61)$
$=100+100$
$=200$
$73 + 49 + 51 + 27$
$=(73+27)+(49+51)$
$=100 + 100$
$=200$
$45 + 48 + 155 + 52$
$=(45+155)+(48+52)$
$=200+100$
$=300$
$(174 + 293) + 126$
$=(174+126)+293$
$=300+293$
$=593$