Describe how you can use mental math to find the product.
15*25
25 = 100/4
so 1500/4, if you can do that in your head
Find the product of 27×60 then explain how you would use mental math to find the product of 27×600
To find the product of 15 and 25 using mental math, you can use the method of multiplication by decomposition.
Step 1: Begin by breaking down both numbers into their tens and units places:
15 = 10 + 5
25 = 20 + 5
Step 2: Multiply the tens places together:
10 * 20 = 200
Step 3: Multiply the cross products:
10 * 5 = 50
5 * 20 = 100
Step 4: Add the partial products together:
200 + 50 + 100 = 350
Therefore, the product of 15 and 25 is 350.
To find the product of 15 multiplied by 25 using mental math, you can use a technique known as the "split and multiply" method. Here's how you can do it:
Step 1: Split both numbers into smaller, more manageable parts.
- For 15, you can split it into 10 and 5.
- For 25, you can split it into 20 and 5.
Step 2: Multiply the parts of each number to get intermediate products.
- Multiply 10 by 20: 10 x 20 = 200.
- Multiply 10 by 5: 10 x 5 = 50.
- Multiply 5 by 20: 5 x 20 = 100.
- Multiply 5 by 5: 5 x 5 = 25.
Step 3: Add up all the intermediate products.
- Add 200 + 50 + 100 + 25 = 375.
Therefore, 15 multiplied by 25 equals 375.
This method allows you to break down larger numbers into simpler calculations, making it easier to perform the multiplication mentally.