Identify Numbers: Identify the numbers involved in the division. We have 10.5 as the dividend and 2.1 as the divisor.Count Decimals: Count the number of decimal places in both the dividend and the divisor. 10.5 has one decimal place, and 2.1 also has one decimal place.Eliminate Decimals: To simplify the division, we can eliminate the decimals by multiplying both the dividend and the divisor by 10. Multiplying 10.5 by 10 gives 105. Multiplying 2.1 by 10 gives 21.Perform Division: Perform the division with the new numbers. Now we have to divide 105 by 21. 105 ÷ 21 = 5Check Result: Check the result. Since we multiplied both the dividend and the divisor by the same number (10), the quotient remains the same. Therefore, the result of the original division (10.5 ÷ 2.1) is the same as the result of the new division (105 ÷ 21), which is 5.

Grade 5

Multiply a decimal by a multi-digit whole number

Full solution

10.5

divided by

2.1

Identify Numbers: Identify the numbers involved in the division. $\newline$ We have $10.5$ as the dividend and $2.1$ as the divisor.
Count Decimals: Count the number of decimal places in both the dividend and the divisor. $10.5$ has one decimal place, and $2.1$ also has one decimal place.
Eliminate Decimals: To simplify the division, we can eliminate the decimals by multiplying both the dividend and the divisor by $10$ . Multiplying $10.5$ by $10$ gives $105$ . Multiplying $2.1$ by $10$ gives $21$ .
Perform Division: Perform the division with the new numbers. $\newline$ Now we have to divide $105$ by $21$ . $\newline$ $105 \div 21 = 5$
Check Result: Check the result. $\newline$ Since we multiplied both the dividend and the divisor by the same number ( $10$ ), the quotient remains the same. Therefore, the result of the original division ( $10.5 \div 2.1$ ) is the same as the result of the new division ( $105 \div 21$ ), which is $5$ .