Can someone answer this?

0.9*0.9

0.09*0.9

0.009*0.9

0.009*0.09

we know that 9*9 = 81, so let's start there.

0.9 * 0.9

one amount has 1 decimal, the second amount has another decimal, so in the product, we must have two decimals, let's do the multiplication without the dot.

09 * 09 = 81

but we must have two decimals, so that becomes 0.81.

0.09 * 0.9

here we do the same, the multiplication without the dot, and then we add as many decimals, in this case is 3 decimals, first term has 2 and the second term has 1 decimal, so the product must have 3 decimals.

009 * 09 = 81

getting those 3 decimals ... 0.081.

0.009 * 0.9

here we do the same

0009 * 09 = 81

the product needs 4 decimals, so ... 0.0081.

0.009 * 0.09

we do the same here

0009 * 009 = 81

since the product needs 5 decimals ... 0.00081.