Can we choose seven of these nine numbers so that the sum is 50? 1, 3, 5, 7, 7, 9, 11, 15, 21

Can we choose seven of these nine numbers so that the sum is 50? 1, 3, 5, 7, 7, 9, 11, 15, 21

Six numbers, 21 + 3 + 5 + 11 + 9 + 1 = 50 or

In 1 / 3, 1 / 2, 5 / 9, 7 / 12, 9 / 15, 11 / 18, the 50th number is ()
First restore these scores, and the law will come out,

It's very simple. 1 / 3, 3 / 6, 5 / 9. The key is to change 1 / 2 into 3 / 6. Then, those who have learned induction can see it very quickly. The general formula is (2n-1) / (3n), where n is a natural number. Just substitute 50 for it. 99 / 150, that is 33 / 50

3.15.9.7.21.1.5.11.7 select 7 numbers to make their sum 50

3+15+9+7+21+1+5+11+7=79
79-50=29
impossible

3.6X2.7+18X0.56-1.8X10%÷10%
Off formula calculation! Can be simple to calculate!

3.6X2.7+18X0.56-1.8X10%÷10%
1.8x 5.4 + 1.8x 5.6 - 1.8 x 1
= 1.5x ( 5.4 + 5.6 -1)
= 1.5 x 10
= 15