Decimal Multiplication: Finding the Correct Decimal Point in 3.5 × 2.4 = 840

Question

Look at the following exercise and determine the correct place of the decimal point:

$3.5\times2.4=840$

00:00 Place the decimal point

00:03 Count the total number of digits after the decimal point

00:06 According to this sum, we'll place the decimal point in the solution

00:09 We'll move the decimal point by the sum of digits

00:12 And this is the solution to the question

In the number -3.5, there is one digit after the decimal point: 5.

In the number 2.4, there is one digit after the decimal point: 4.

In other words, we have two digits after the decimal point.

Therefore we will move the decimal point two places to the left to get our answer: 8.40.

$\text{8}.40$