Question

A tank that is 40% full contains 648 gallons of water. Use a double number line to find the maximum capacity of the water tank.

Answer 1

Here is what the numbers would look like on a number line.  They are lined up.

10%  20%  30%  40%  50%  60%  70%  80%  90%  100%
162   324   486   648   810   972   1134  1296  1458  1620

The maximum capacity is 1620 gallons of water.