I learnt a lot of strategy, I learned number line, place value, rounding and compensation, and lastly borrowing numbers.
First I learnt number line, number line is a strategy when you add the small number and try to make the 1 digit number even.
Then I learnt place value and rounding and compensation. Place value is when adding the smallest numbers, then the bigger number, then the last numbers if there is any, rounding and compensation is rounding the number to the nearest ten.
Lastly I learnt borrowing numbers, borrowing numbers is when you take a number from one of the numbers to make the other number even, then add it to the other number then add it all to find the answer.