Addition & Subtraction Drills
💡Work left to right: add the tens first, then the ones, then combine. For subtraction, it is usually faster to count up than to take away.
Try it — add two numbers left to right
liveAdd the bigger place values first, then the rest.
- 1
Add the tens part first
68 + 50 = 118
- 2
Then add the ones
118 + 7 = 125
⏱️ Practice against the clock
A worked example
For 68 + 57, add the tens (60 + 50 = 110), add the ones (8 + 7 = 15), then combine: 125. For 83 − 67, count up: 67 to 70 is 3, 70 to 83 is 13, so 16.
Why left to right actually helps
The way you learned addition on paper, lining up columns and starting from the right, is the slowest way to do it in your head. You end up holding every digit hostage until the last carry lands.
Flip it and lead with the big numbers. For 68 + 57, do 60 + 50 first (110), then 8 + 7 (15), then put them together for 125. You get a rough answer almost straight away, and there is only ever one running number to keep track of instead of a stack of carries.
For subtraction, stop taking away
Borrowing across a row of zeros is where most people lose the thread. So do not borrow. Count up instead.
Say you want 83 − 67. Step from 67 up to 70, that is 3. Then 70 up to 83, that is 13. Add them and you are done: 16. It is the same thing a shopkeeper does handing back change, and since you only ever move forward to round numbers, there is nothing to borrow.
Questions people ask
Why work left to right instead of right to left? ▾
The biggest digits set the size of the answer, so starting on the left keeps a running estimate in front of you and cuts down on carrying mistakes.
How long before this feels automatic? ▾
Most people notice a real difference after a week or two of short daily sets. Speed comes from recall, and recall comes from reps, not from any single trick.