Building skyscrapers with numbers.
Adding numbers with two or more digits using columns.
Ancient merchants used abacuses to handle large sums.
Line up the right side perfectly.
Plain English: When numbers get too big for fingers, we stack them. We match the Ones with Ones, and Tens with Tens.
Real-world example: Adding up the prices of three different video games to see if you have enough allowance.
Lining up the numbers on the LEFT. Always line them up on the RIGHT!