To get the product of2×3×15,billhas to press the keys of his calculator seven times: 2×3×15=bill wants to multiply all numbers from 3to21,using his calculator. at least ,how many times will he press the keys of his calculator?

The table below shows the approximate masses of a dust particle and a grain of pollen. dust particle 0.000000778 g grain of pollen 0.00000000155 g the mass of a dust particle can be estimated and written in the form a × 10^b, where a = 8 and b = the mass of a grain of pollen can be estimated and written in the form a × 10^b, where a = 2 and b = based on the estimates, the mass of a dust particle is approximately blank times larger than the mass of a grain of pollen.