内容正文:
第二单元计算专项:没有括号的混合运算
知识点梳理
1. 没有括号的同级混合运算(只有加减法,或只有乘除法):从左往右,依次计算。
例:32+18-25,先算32+18,再用结果减25;48÷6×2,先算48÷6,再乘2。
2. 没有括号的两级混合运算(既有乘/除,又有加/减):先算乘、除法,后算加、减法。
例:20+5×3,先算乘法5×3,再算加法;45-12÷3,先算除法12÷3,再算减法。
⚠️ 注意:只有乘除或者只有加减,才是同级;乘除优先级高于加减,不要从左往右随意计算。
专项练习
考点1:只有加减的同级混合运算(从左往右算)
(1)25+13-18
(3)48+32-50
(5)36+44-29
(7)52+28-37
(9)19+61-45
(11)41+29-53
(13)33+47-60
(15)27+53-41
(2)76-24+15
(4)90-45+26
(6)65-17+23
(8)83-31+14
(10)72-28+33
(12)58-16+27
(14)86-55+19
(16)69-39+25
考点2:只有乘除的同级混合运算(从左往右算)
(1)4×6÷3
(3)5×8÷4
(5)3×6÷2
(7)7×4÷2
(9)2×9÷3
(11)8×3÷6
(13)6×6÷9
(15)9×2÷6
(2)36÷4×2
(4)42÷7×5
(6)64÷8×3
(8)24÷3×6
(10)54÷6×4
(12)18÷2×7
(14)40÷5×8
(16)28÷4×9
考点3:先乘后加(两级运算,无括号)
(1)12+4×5
(3)34+2×8
(5)42+6×3
(7)28+4×4
(9)22+8×2
(11)37+5×3
(13)14+6×4
(15)21+9×2
(2)25+3×6
(4)18+5×4
(6)15+7×2
(8)31+2×9
(10)16+3×7
(12)29+4×6
(14)44+2×5
(16)35+3×5
考点4:先乘后减(两级运算,无括号)
(1)30-4×5
(3)50-6×4
(5)36-5×3
(7)45-4×6
(9)54-8×5
(11)48-5×7
(13)63-9×4
(15)40-3×5
(2)42-3×7
(4)27-2×8
(6)60-7×6
(8)33-3×9
(10)28-2×6
(12)39-4×8
(14)55-6×3
(16)51-7×2
考点5:先除后加(两级运算,无括号)
(1)10+12÷3
(3)25+14÷2
(5)15+28÷7
(7)22+36÷9
(9)34+16÷4
(11)13+40÷8
(13)31+48÷6
(15)19+35÷5
(2)18+24÷4
(4)32+18÷6
(6)40+30÷5
(8)17+42÷7
(10)21+54÷6
(12)29+27÷3
(14)24+10÷2
(16)36+21÷7
考点6:先除后减(两级运算,无括号)
(1)15-12÷3
(3)20-14÷2
(5)24-28÷7
(7)35-36÷9
(9)40-16÷4
(11)21-40÷8
(13)45-48÷6
(15)32-35÷5
(2)30-24÷4
(4)42-18÷6
(6)50-30÷5
(8)25-42÷7
(10)33-54÷6
(12)36-27÷3
(14)28-10÷2
(16)41-21÷7
对应应用题
1. 商店里每盒铅笔有6支,买4盒,另外还有10支散装铅笔。一共有多少支铅笔?
2. 一本书一共80页,小明每天看9页,看了5天,还剩多少页没有看?
3. 妈妈买了3袋苹果,每袋有8个,吃掉12个,还剩多少个苹果?
4. 一共有36块糖果,平均分给4个小朋友,再加上5块糖果,现在一共有多少块?
5. 有一堆铁丝,每段长4米,做6段,另外还有18米铁丝,铁丝一共长多少米?
6. 一支钢笔8元,5本笔记本一共30元,买一支钢笔和一本笔记本一共要花多少钱?
7. 果园里有4行桃树,每行7棵,梨树有15棵,桃树和梨树一共有多少棵?
8. 一盒羽毛球有45个,拿走3筒,每筒5个,还剩多少个羽毛球?
9. 一张儿童票5元,成人票每张12元,1张成人票加3张儿童票一共多少元?
10. 有54个橘子,每盘放9个,吃掉2盘橘子,还剩下多少个橘子?
第 1 页 共 8 页
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参考答案
考点1:只有加减的同级混合运算
(1)25+13-18 = 38-18 = 20
(2)76-24+15 = 52+15 = 67
(3)48+32-50 = 80-50 = 30
(4)90-45+26 = 45+26 = 71
(5)36+44-29 = 80-29 = 51
(6)65-17+23 = 48+23 = 71
(7)52+28-37 = 80-37 = 43
(8)83-31+14 = 52+14 = 66
(9)19+61-45 = 80-45 = 35
(10)72-28+33 = 44+33 = 77
(11)41+29-53 = 70-53 = 17
(12)58-16+27 = 42+27 = 69
(13)33+47-60 = 80-60 = 20
(14)86-55+19 = 31+19 = 50
(15)27+53-41 = 80-41 = 39
(16)69-39+25 = 30+25 = 55
考点2:只有乘除的同级混合运算
(1)4×6÷3 = 24÷3 = 8
(2)36÷4×2 = 9×2 = 18
(3)5×8÷4 = 40÷4 = 10
(4)42÷7×5 = 6×5 = 30
(5)3×6÷2 = 18÷2 = 9
(6)64÷8×3 = 8×3 = 24
(7)7×4÷2 = 28÷2 = 14
(8)24÷3×6 = 8×6 = 48
(9)2×9÷3 = 18÷3 = 6
(10)54÷6×4 = 9×4 = 36
(11)8×3÷6 = 24÷6 = 4
(12)18÷2×7 = 9×7 = 63
(13)6×6÷9 = 36÷9 = 4
(14)40÷5×8 = 8×8 = 64
(15)9×2÷6 = 18÷6 = 3
(16)28÷4×9 = 7×9 = 63
考点3:先乘后加
(1)12+4×5 = 12+20 = 32
(2)25+3×6 = 25+18 = 43
(3)34+2×8 = 34+16 = 50
(4)18+5×4 = 18+20 = 38
(5)42+6×3 = 42+18 = 60
(6)15+7×2 = 15+14 = 29
(7)28+4×4 = 28+16 = 44
(8)31+2×9 = 31+18 = 49
(9)22+8×2 = 22+16 = 38
(10)16+3×7 = 16+21 = 37
(11)37+5×3 = 37+15 = 52
(12)29+4×6 = 29+24 = 53
(13)14+6×4 = 14+24 = 38
(14)44+2×5 = 44+10 = 54
(15)21+9×2 = 21+18 = 39
(16)35+3×5 = 35+15 = 50
考点4:先乘后减
(1)30-4×5 = 30-20 = 10
(2)42-3×7 = 42-21 = 21
(3)50-6×4 = 50-24 = 26
(4)27-2×8 = 27-16 = 11
(5)36-5×3 = 36-15 = 21
(6)60-7×6 = 60-42 = 18
(7)45-4×6 = 45-24 = 21
(8)33-3×9 = 33-27 = 6
(9)54-8×5 = 54-40 = 14
(10)28-2×6 = 28-12 = 16
(11)48-5×7 = 48-35 = 13
(12)39-4×8 = 39-32 = 7
(13)63-9×4 = 63-36 = 27
(14)55-6×3 = 55-18 = 37
(15)40-3×5 = 40-15 = 25
(16)51-7×2 = 51-14 = 37
考点5:先除后加
(1)10+12÷3 = 10+4 = 14
(2)18+24÷4 = 18+6 = 24
(3)25+14÷2 = 25+7 = 32
(4)32+18÷6 = 32+3 = 35
(5)15+28÷7 = 15+4 = 19
(6)40+30÷5 = 40+6 = 46
(7)22+36÷9 = 22+4 = 26
(8)17+42÷7 = 17+6 = 23
(9)34+16÷4 = 34+4 = 38
(10)21+54÷6 = 21+9 = 30
(11)13+40÷8 = 13+5 = 18
(12)29+27÷3 = 29+9 = 38
(13)31+48÷6 = 31+8 = 39
(14)24+10÷2 = 24+5 = 29
(15)19+35÷5 = 19+7 = 26
(16)36+21÷7 = 36+3 = 39
考点6:先除后减
(1)15-12÷3 = 15-4 = 11
(2)30-24÷4 = 30-6 = 24
(3)20-14÷2 = 20-7 = 13
(4)42-18÷6 = 42-3 = 39
(5)24-28÷7 = 24-4 = 20
(6)50-30÷5 = 50-6 = 44
(7)35-36÷9 = 35-4 = 31
(8)25-42÷7 = 25-6 = 19
(9)40-16÷4 = 40-4 = 36
(10)33-54÷6 = 33-9 = 24
(11)21-40÷8 = 21-5 = 16
(12)36-27÷3 = 36-9 = 27
(13)45-48÷6 = 45-8 = 37
(14)28-10÷2 = 28-5 = 23
(15)32-35÷5 = 32-7 = 25
(16)41-21÷7 = 41-3 = 38
应用题参考答案
1. 6×4+10 = 24+10 = 34(支) 答:一共有34支铅笔。
2. 80-9×5 = 80-45 = 35(页) 答:还剩35页没有看。
3. 3×8-12 = 24-12 = 12(个) 答:还剩12个苹果。
4. 36÷4+5 = 9+5 = 14(块) 答:现在一共有14块糖果。
5. 4×6+18 = 24+18 = 42(米) 答:铁丝一共长42米。
6. 8+30÷5 = 8+6 = 14(元) 答:一共要花14元。
7. 4×7+15 = 28+15 = 43(棵) 答:桃树和梨树一共有43棵。
8. 45-3×5 = 45-15 = 30(个) 答:还剩30个羽毛球。
9. 12+3×5 = 12+15 = 27(元) 答:一共27元。
10. 54-9×2 = 54-18 = 36(个) 答:还剩36个橘子。
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