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Mathematical thinking in the third grade of primary school
(1) Suppose there is money left after spending the second time.

X/2+3+ 1=X

X=8

Suppose you have money left after the first consumption.

Y/2+2+8=Y

Y=20

Let's start by saying that this person has Z yuan.

Z/2+ 1+20=Z

Z=42

In fact, there is a rule-

The last remaining money is 1*2+6=8.

The second 8*2+4=20

20*2+2=42 for the first time

What do you see?

(2) A solid square is a square ~2 1 chess piece added in a row horizontally and vertically, and one chess piece must be used for * * *, so a new row has (21-1)/2+1=1/kloc.

It used to be10 *10 =100 ~ Let's make a picture if we can't figure it out ~

(3) 160/20-2=6,, seems to have nothing to do with those 20 young pioneers.

(4) Look upstairs-

Suppose my sister walked for x minutes.

45X=50(X-5)

45X=50X-250

-5X=-250

X=50

50 * 45 = 2250m

Sure enough, it's a three-level question, as long as it's set, it's no problem ~