How do you write 17 and 3/10 in a decimal point

We have a decimal system, which means that each column of our number system has a value of increasing powers of ten as you move from right to left.  And each column is of decreasing powers of ten as you move from left to right.

10^n10^2, 10^1, 10^0 (decimal point) 10^-1, 10^-210^-n

So the decimal point marks the transition to negative powers...

10^n, 100, 10, 1 (decimal point) 1/10, 1/100...1/10^n

All of this was the long way of explaining that the first place after the decimal point is the tenths column so if you have 3 tenths, you have 0.3...In this case you have 17 3/10 so

17.3