Mathematics Class 7
Large Numbers Around Us
Lakhs and crores: read, compare, round, estimate and multiply big numbers quickly.
14 lessons · ~85 min total
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Lessons in this topic
- 0 Start here Big numbers: columns, commas, reading, comparing, rounding, estimating and quick times. · 3 min You are here
- 1 Past the thousands column Ten thousand, lakh and crore come after the thousand — each one is ten of the column before it. · 6 min
- 2 Two ways to group the same digits The Indian pattern and the international pattern place commas differently. Neither one changes the number. · 6 min
- 3 Reading a large number out loud The Indian commas cut a number into named groups. Read each group as an ordinary number. · 6 min
- 4 Which large number is bigger Count the digits first. If the counts match, walk left to right and stop where they first differ. · 6 min
- 5 Rounding to a place you choose Pick a place. The part of the number below it says whether you go up or go down. · 6 min
- 6 Estimate before you compute A rough answer, worked out first, catches a wrong answer before you trust it. · 7 min
- 7 How big a lakh really is Drawn as dots, or counted one a second, a lakh and a crore stop feeling like the same thing. · 7 min
- 8 Round which way? What you need decides: round up, round down, or keep it exact. · 6 min
- 9 Estimates on one side of the answer Round both numbers the same way. The answer's side is then known. · 7 min
- 10 Quick times 5, 25 and 125 Times 5, 25 or 125: work them with 10, 100 or 1000. · 7 min
- 11 Checkpoint: rounding and quick times Check rounding, estimates that are too big or small, and quick times. · 5 min
- 12 The big picture Ten ideas, tied back together. · 5 min
- 13 Track quiz Cheat-sheet table plus a reveal quiz — one question per idea. · 8 min
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