Addition of two numbers:
Adding a 2-digit number and a 1-digit number involves adding a number in the tens place and ones place (the 2-digit number) with a number that only has a ones place (the 1-digit number). The process starts by adding the ones digits first. If the result is more than 9, you regroup (carry over) the extra value to the tens place.
Step-by-Step Process:
- Align the numbers by place value (ones under ones, tens under tens).
- Add the ones place digits. If the sum is greater than 9, write down the ones digit and carry over the tens digit to the next column.
- Add the tens place. If there is a carry-over from the ones place, add it to the tens digit of the 2-digit number.
Example 1:
Without regrouping, add numbers 34 and 5.
Solution:
- Write the numbers aligned by place value:
34
+ 5
----
- Add the ones place:
- 4 + 5 = 9. Write 9 in the ones place.
- Move to the tens place:
- There's no number to add to 3, so just bring down the 3.
- Final solution:
34
+ 5
----
39
So, 34 + 5 = 39.
Example 2:
With Regrouping, Add 57 and 8.
Solution:
- Write the numbers aligned by place value:
57
+ 8
----
- Add the ones place:
- 7 + 8 = 15. Write 5 in the ones place and carry over 1 to the tens place.
- Move to the tens place:
- Final solution:
57
+ 8
----
65
So, 57 + 8 = 65.
Example 3:
Lily has 46 apples, and her friend gives her 7 more apples. How many apples does Lily have in total?
Solution:
- Write the numbers to add:
57
+ 8
----
- Add the ones place:
- 7 + 8 = 15. Write 5 in the ones place and carry over 1 to the tens place.
- Move to the tens place:
- Final solution:
57
+ 8
----
65
So, 57 + 8 = 65.
