(101+102+103+...+199)-(90+92+94+...+188)

(101+102+103+...+199)-(90+92+94+...+188)

Have you ever learned the arithmetic sequence? If you have, just use that one. If not, look at the formula: the number in brackets in front = (101 + 199) * 99 / 2 = 14850, the number in brackets behind is (188-90) / 2 + 1, that is, 50 numbers, so the number in brackets behind = (90 + 188) * 50 / 2 = 6950, so the total formula = 14850-6950 = 7900

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Bonding (bonding, bonding, cementation, gluing) refers to the technology of bonding the surface of homogeneous or heterogeneous objects with adhesives. It has the characteristics of continuous stress distribution, light weight, or sealing, and low process temperature. Bonding is especially suitable for the connection of different materials, different thicknesses, ultra thin specifications and complex components

How to simplify the operation of 36 * 48 + 72 * 26

36×48＋72×26
＝36×48＋36×26×2
＝36×48＋36×52
＝36×（48＋52）
＝36×100
＝3600

Simple calculation: 48 / 36 and 49 / 12

48 / 36 / 49
=36÷12+48/49÷12
=3+4/49
=3 and 4 / 49

1 and 1 / 6 + 3 and 1 / 12 + 5 and 1 / 20 + 7 and 1 / 30 + 9 and 1 / 42
Simple operation

1/6=1/2-1/3,1/12=1/3-1/4.
So the original formula = 1 + 3 + 5 + 7 + 9 + (1 / 2-1 / 3) + (1 / 3-1 / 4) + (1 / 4-1 / 5) + (1 / 5-1 / 6) + (1 / 6-1 / 7)
=(1+3+5+7+9）+（1/2-1/7）
=15+5/14
=15 and 5 / 14

Simple operation of 2013 × 2 / 13 + 2013 △ 13 × 11 (within 5 minutes)

2013 × 2 / 13 + 2013 △ 13 × 11
=2013 × (2 / 13) + 2013 × 11 △ 13
=2013 × (2 / 13) + 2013 × (11 / 13)
=2013 × (2 / 13 + 11 / 13)
=2013

-/-11 / 3 / * / - 0.25 / - - 5 and 1 / 4) * (+ 11 / 3) and write the calculation process

-/-11 / 3 / * / - 0.25 / - - 5 and 1 / 4) * (+ 11 / 3)
=-11/3*0.25+5.25*11/3
=11/3*（-0.25+5.25）
=11/3*5
=55/3
=18 and 1 / 3

What is 31 out of 50 times 45 plus 19 out of 50 divided by 1 out of 45
Simple. Have details

Is this the formula: (31 / 50) * 45 + (19 / 50) / (1 / 45)
If yes: = (31 / 50) * 45 + (19 / 50) * 45
=（31/50+19/50）*45
=(50/50)*45
=45

Xiaogang's grandfather's age minus 5, divided by 4, then minus 6, multiplied by 10 equals 100, you can guess Xiaogang's grandfather this year

(100/10+6)x4+5=69

Grandfather's age plus 30, divided by 9, minus 2 equals 9, how old is grandfather this year

(9 + 2) × 9-30 = 69 years old
I wish you a higher level of learning, mathematics counseling group to solve your problems!