Who knows the question of the third grade of elementary school

abcd

DCBA is still a four-digit figure because DCBA.

So A must be 1, otherwise ABCD 9 would not be a four-digit number.

And since the single digit of d 9 is 1, d must be 9

Write the equation as.

1 bc99cb 1

Because b 9 has no carry (otherwise a 9 carry product would not be a four-digit number), b must be 0 (because a=1).

And because the single digit of c 9 8 is 0, c must be 8

i.e. abcd=1089

Check: 1089 9 = 9801

So a=1 b=0 c=8 d=9

A is 1, B is 0, C is 8, and D is 9

Let's start with both sides.

It's too hard, do you want to think about it mathematically or something else?

a=1 b=0

c=8 d=9

By: Invincible 321 - Jinshi Origin 8th Level 11-1 11:51abcd

DCBA is still a four-digit figure because DCBA.

So A must be 1, otherwise ABCD 9 would not be a four-digit number.

And since the single digit of d 9 is 1, d must be 9

Write the equation as.

1 bc99cb 1

Because b 9 has no carry (otherwise a 9 carry product would not be a four-digit number), b must be 0 (because a=1).

And because the single digit of c 9 8 is 0, c must be 8

i.e. abcd=1089

Check: 1089 9 = 9801

Cut a maximum square:

10-6 = 4 (cm).

4 2 + 6 2 = 20 (cm).

How big is a square?

Eternal rounding method: the number greater than the equal circle is quietly 5 into a cluster of grinding bits.

The small seepage bucket is directly rounded off at the number of 5.

So 38 18 is rounded up to 38 about 40 18 about 20 so 40 20 800

53 68 Because 3 is less than 5, just drop it.

53 about 50, 68 about 70

（7＋5）×2＝24

The circumference of the largest rectangle in the picture is 24 cm.

1. Five-pointed star = 5 squares;

2. Pentagram + square = 300;

3. Square.

Four, five-pointed star.

300-50 = 250 or.

A five-pointed star is equivalent to five squares, then a five-pointed star plus a square is equivalent to 6 squares, and according to the title, a five-pointed star plus a square is equal to 300, so a square is 50, then a five-pointed star is 50 x 5=250

(8) Use a 12 cm long wire to form a square, the side length of this square is 3 cm, and the area is 9 square cm.

9) The second half of the question is incomplete.

10) Obtained from five stars + blocks = 300: five stars = 300 - blocks, and because five stars = 5 blocks.

So 5 blocks = 300 - 6 blocks = 300

Block = 50, so five stars = 300-50 = 250.