Question

There were 57 people sitting in a circle. One person throws the ball to the 21st person to her right. The catcher then throws it to the 21st person to his right, and it goes this way around the circle. How many total throws are there to get the ball back to the first person? Tip: Do not use images that show a different and simpler version of the game, with only nine people, each throwing the ball to the second person on the right.

a.57
b.21
c.57 × 21
d.57/21
e.78
f.36
g.7
h.19
i.133
j.63​

Answer 1

19

Explanation:

We need to find the LCM of 57 and 21 and divide by 21. To do that we need to find the GCF.

57/3 = 19

21/3 = 7

The GCF is 3, which is he highest whole number that if 57 and 21 are divided by it, the results would still be whole numbers.

21/3 = 7

57x7 = 399

399/21 = 19