Dividing by a whole number is nothing new — the decimal point just comes along for the ride. Dividing by a decimal takes one extra trick: moving both decimal points before you divide.
When the number you're dividing by (the divisor) is already a whole number, division works exactly like you'd expect — just keep the decimal point in the quotient (the answer) directly above the decimal point in the number you're dividing.
6 ÷ 4 = 1 remainder 2. Bring down the 4 to make 24, and 24 ÷ 4 = 6. The decimal point in the answer sits directly above the one in 6.4 — no moving, no counting, just carry it straight across.
Dividing by a decimal (like 1.2) is trickier, so we turn it into a problem we already know how to solve: move the divisor's decimal point to the right until it becomes a whole number, and move the dividend's decimal point the same number of places. This doesn't change the answer — you're just multiplying both numbers by the same power of 10.
Try 0.6 ÷ 0.03. The divisor 0.03 needs 2 places to become whole (3), so the dividend 0.6 needs to move 2 places too — but it only has 1 digit after the point. Add a zero to make room:
Work through each problem in two stages: first figure out how many places to move the decimal point, then move the dividend's point to rewrite the problem.
Here's the division problem.