GED Mathematical Reasoning: Money – Multiplying and Dividing
Multiply $2.34 by 5.
We’ll multiply this as we would multiply the whole numbers 234 and 5.
5 multiplied by 4 is equal to 20. Place the zero in the ones place and carry the 2 – writing it above the 3.
Next, multiply 5 times 3 and then add the 2. The result is 17. Place the 7 in the tens place and carry the 1.
Finally, multiply 5 times 2 and add the 1. The result is 11, which we write to the left of the 7.
For our final answer, we will be sure to include the decimal point and dollar sign.
Since there are two digits to the right of the decimal in the dollar amount given in the original problem ($2.34), we place the decimal point in our final answer so that there are two digits to the right of it. Therefore, our final answer is: $11.70
Let’s pause to discuss the importance of evaluating an answer for reasonableness. When completing a math problem, it is beneficial to stop and ask ourselves: Does the answer seem reasonable given the original values? Evaluating an answer for reasonableness is a way to double check our work and catch mistakes we may have made. For example, is $11.70 a reasonable answer for $2.34 times 5?
Well, $2.34 is very close to $2. And if we multiply 2 by 5, we can quickly calculate the result to be 10. Since $2.34 is slightly higher than $2, we can expect the result of $2.34 times 5 to be slightly higher than $10. Since it is, at $11.70, we can feel confident that we did the problem correctly and our answer is right.
Divide: $8.92 by 4
We will write this using the division bracket. The dividend of $8.92 goes underneath the bracket and the divisor of 4 sits outside to the left.
4 goes into 8 two times. Place a 2 on top of the division bracket, directly over the 8.
Now we multiply – 2 times 4 equals 8. Place this product underneath the 8 of the dividend and subtract. 8 minus 8 equals zero.
Although the remainder is zero, we continue on because there is a digit to bring down. Bring down the 9.
Don’t let the zero throw you off, now we repeat the process using 09 – or just 9 – as our new dividend. 4 goes in to 9 twice. We write the 2 on top of the bracket, directly over the 9 and to the right of the decimal point.
2 times 4 is equal to 8. Write the 8 underneath the 9 and subtract 8 from 9. The result is 1. Bring down the 2.
Now repeat the process, using the number 12 as our new dividend. 4 goes into 12 three times. Write the number 3 on top of the bracket directly over the 2.
3 times 4 equals 12. Write 12 underneath the 12 and subtract. Because the remainder is zero and there are no digits remaining to bring down, the process is complete.
The final answer is: $2.23.
Now, does our answer make sense? $8.92 is very close to $8. And we can quickly calculate that 8 divided by 4 is 2. Since $8.92 is slightly higher than $8, we should expect $8.92 divided by 4 to be slightly more than $2. And it is at $2.23. So we can feel confident that we worked the problem correctly and that our answer is right.