# Easy Math calculation for kids

#### There are a couple of strange things about the first few prime numbers,

153 = 1^3 + 3^3 + 5^3

And 3 and 5 can also both be expressed as the difference between two square

3 = 2^2 – 1^2
5 = 3^3 – 2^2

#### With number 4 the secret steps in the multiplication tables become a little more intricate.

4*1 = 4 ———————————– 4
4*2 = 8 —————————- 8
4*3 = 12 —————— 1+2 = ——— 3
4*4 = 16 —————— 1+6 = — 7
4*5 = 20 —————— 2+0 = ——— 2
4*6 = 24 —————— 2+4 = — 6
4*7 = 28 —-2+8=10—- 1+0 = ———– 1
4*8 = 32 —————— 3+2 = — 5
4*9 = 36 —————— 3+6 = ——— 9
4*10 = 40 —————– 4+0 = — 4
4*11 = 44 —————– 4+4 = ——— 8
4*12 = 48 —4+8=12 ——- 1+2=– 3
4*13 = 52 —————– 5+2 = ——— 7
4*14 = 56 —5+6=11——– 1+1=– 2
4*15 = 60 —————– 6+0 = ——— 6
4*16 = 64 —6+4=10——– 1+0=– 1

#### That it is easier to add round numbers like 40 or 50 than numbers ending in 7, 8, or 9. If you round these awkward numbers up by adding 3, 2 or 1 the calculation is not much longer, and is easier. Instead of 49+52 = 101 think of it as 50 (that is 49+1) + 52 = 102-1 = 101

Other example
215
426
513
112
328
—-

First add the figure in the hundreds column and hold the total, 1500, in your head. Now add the total of the tens column, 70, to it. To this total 1570 add the sum of the units column, 24, to arrive at the final total of 1594

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