Elephants, Tigers, and Leopards | Maths Grade 4 CBSE

Play with it

Six big-sum ideas

Adding and subtracting big numbers, column by column. Tap each term to see what it means.

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Learn

Add column by column, starting from the ones, then tens, then hundreds.
When a column adds up to 10 or more, write the ones digit and carry the ten over.
Line the numbers up neatly so each place sits under the right place.

Worked example. A reserve counts 1240 deer in one part and 1380 in another. How many in all?

1240 + 1380: ones 0, tens 4+8=12 (carry 1), hundreds 2+3+1=6, thousands 1+1=2 — that is 2620 deer.

Subtract column by column from the ones, taking the smaller digit from the bigger.
If the top digit is too small, borrow ten from the next column on the left.
Always start from the ones, never from the other end.

Worked example. There were 3500 birds and 1200 flew away. How many are left?

3500 − 1200: ones 0, tens 0, hundreds 5−2=3, thousands 3−1=2 — that is 2300 birds.

Estimating means rounding to guess the answer fast — handy to check your work.
2980 + 1010 is about 3000 + 1000 = 4000, close to the exact 3990.
Addition and subtraction undo each other, so you can check a sum by taking away.

Worked example. Estimate 4120 + 2890 by rounding to the nearest thousand.

About 4000 + 3000 = 7000 (the exact answer is 7010 — very close).

Common mix-up: Always begin from the ones column on the RIGHT. Starting from the left and forgetting to carry or borrow gives a wrong answer.

Where you’ll meet it

Forest officers add up animal counts from many areas to know how many tigers or elephants live there.

Adding visitor numbers across days, or finding how many tickets are left, uses big-number sums.

Adding up savings, or finding change from a big note, is everyday addition and subtraction.

Check yourself

Ten friendly questions — mostly multiple-choice with one assertion–reason — to check your big-number sums.

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