You could increase their values so that they are whole numbers by multiplying both by 100. That gives you 840 ÷ 21, which is 40. That is the answer to 8.4 ÷ 0.21 too.
84 divided by 2 is 42
84 divided by 1 is equal to 84.
64 divided into 84 = 0.7619047619047619
84 divided by 32= = 2.625
84
21
0.6269
84
0.0092
3
84
7