Answer:
315
Explanation:
Here is step-by-step how to calculate 21 times 15 using long multiplication:
Step 1: Setup
Set up your multiplication problem like this:
2 1
x 1 5
Step 2: Multiply
1 x 5 = 5. Put 5 below the line and 0 as a reminder on top:
0
2 1
x 1 5
5
Step 3: Multiply
5 x 2 = 10. Take 10 and add 0 from the previous step to get 10. Enter 10 at the bottom:
2 1
x 1 5
1 0 5
Step 4: Add 0
Enter a 0 at the bottom right as a place holder, because you now move over one digit:
2 1
x 1 5
1 0 5
+ 0
Step 5: Multiply
1 x 1 = 1. Put 1 below the line and 0 as a reminder on top:
0
2 1
x 1 5
1 0 5
+ 1 0
Step 6: Multiply
1 x 2 = 2. Take 2 and add 0 from the previous step to get 2. Enter 2 at the bottom:
2 1
x 1 5
1 0 5
+ 2 1 0
Step 7: Add to get answer
Add up the bottom two numbers (105 + 210 = 315) to get the answer:
2 1
x 1 5
1 0 5
+ 2 1 0
= 3 1 5
The bottom line is the answer. Therefore, 21 times 15 equals:
315