Question

what looks like 21 individual rings around the girls neck is actually 21 turns of a coil of brass. Each turn has circumference of 40cm. Calculate in cm the total length of brass used to make the girls neck ring​

Answer 1

If each turn of the brass coil has a circumference of 40cm, then the length of one turn is 40cm. Since there are 21 turns in total, we can find the total length of brass used by multiplying the length of one turn by the number of turns:

Total length of brass = length of one turn x number of turns
Total length of brass = 40cm x 21
Total length of brass = 840cm

Therefore, the total length of brass used to make the girl's neck ring is 840cm.