Multiplying decimal numbers may seem complicated, but it's actually quite simple if you know how to multiply whole numbers. The method for multiplying decimal numbers is the same as for whole numbers, as long as we remember to put the decimals back in the final result. So how? Follow these steps to find out.
Step
Step 1. Align the numbers with each other
If one number has more digits, place it above the other. Let's say we multiply 0.43 by 0.06. Align one row of numbers on top of another, above the multiplication line.
Step 2. Multiply the numbers and ignore the decimal point
Now multiply the numbers the same as regular multiplication. Here's how we'll multiply 0.43 and 0.06:
- Start by multiplying 6 in 0.06 by 3 in 0.43 to get 18. Write "8" under 6 and bring 1 over 4.
- Multiply 6 by 4 at 0.43 to get 24. Add 24 by 1 above 4 to get 25. The top row will be 258.
- When multiplying 0.43 by 0 the result is 0, so there is no need to write anything down.
- The answer is 258 when the decimal point is ignored.
Step 3. Count all the numbers to the right of the two decimal points
There are two numbers to the right of 0, 43 (4 and 3), and there are two numbers to the right of 0.06 (0 and 6). Therefore, add 2 by 2 so that the result is 4, this is the number of decimal points moved.
Step 4. Move the decimal point in the result to the left several times
Since we're counting 4 numbers, start with the decimal point at the end of the whole number 258, and move it four times to the left starting from the right of number 8. We'll move once to the left past the 2 in 258.
Step 5. Fill the additional space with zeros
Since there is a blank space between the decimal point and the number 2, fill it with zeros. 258 becomes "0.0258."
Step 6. Check the calculation results
To make sure that 0.43 multiplied by 0.06 is indeed 0.0258, we can divide 0.0258 by 0.06 to make sure the result is 0.43. So, 0.0258 0.06 = 0.43. Check the calculation by dividing the result of the answer by one of the numbers so that the result is another number. Therefore, we can divide 0.0258 by 0.43 to give 0.06. Is it true? 0.0258 0.43 = 0.06. Or, 0.43 0.06 = 0.0258.
Tips
- After moving the decimal point to the front of the number, move the decimal point one step forward.
- Estimate. A number that is too small like the example problem above will have a result that is close to zero.
- We can also think of this number as an integer. Multiply both numbers as integers. Then check the calculation by dividing it. Then find out where the decimal point should be written.
- Multiplying decimal numbers is exactly the same as multiplying whole numbers, with the addition that we must return the exact number of decimal places in the final result.
