If 10% of a number is 7, what is 80% of the number?

Step-by-step explanation:

Note that 80% is 8 times 10%.

Thus, we could start with "If 10% of a number is 7" and multiply both quantities by 8:  "80% of a number is 56."

Think:

10% of a number is 7,

20% is 14,

50% is 35,

70% is 49, and

80% is 56.

300pi

step-by-step explanation: