Adding 4-digit numbers

Your book, Maths Mela (Chapter 10), tells us that India is home to many elephants, tigers and leopards. Karnataka has 6049 elephants and Kerala has 3054. How many is that in all? First estimate: 6049 is about 6000 and 3054 is about 3000, so the answer is about 9000.

Now add in a Th-H-T-O table, starting with the ones. Ones: 9 + 4 = 13 ones. 10 ones make 1 ten, so write 3 and carry 1 ten. Tens: 4 + 5 + 1 = 10 tens. 10 tens make 1 hundred, so write 0 and carry 1 hundred. Hundreds: 0 + 0 + 1 = 1. Thousands: 6 + 3 = 9. The answer is 9103, close to our estimate of 9000.

We can add three numbers in the same way. The book adds 1355, 1131 and 1817 leopards. Ones: 5 + 1 + 7 = 13, write 3, carry 1. Tens: 5 + 3 + 1 + 1 = 10, write 0, carry 1. Hundreds: 3 + 1 + 8 + 1 = 13, write 3, carry 1. Thousands: 1 + 1 + 1 + 1 = 4. The total is 4303.

Remember: 10 ones = 1 ten, 10 tens = 1 hundred, and 10 hundreds = 1 thousand. Whenever a column makes 10 or more, carry to the next column.