Question

Dev thinks of a whole number.He multiplies it by 4.He rounds his answer to the nearest 10.The result is 50.

Write all the possible numbers that Dev could have started with.

Answer 1

There is only one answer, which is 4×12. Because 4×12=48, then rounded is 50, but 4×11=44 and can't be rounded to 50, and 4×13=52 and can't be rounded to 50.