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NCERT · Ganita Prakash · Volume 1 · Chapter 1
Large Numbers Around Us
19 videos in this chapter
Understanding a lakh
2 videos
Chapter 1
Build One Lakh from Familiar Groups
2:51
Build One Lakh from Familiar Groups
You'll learn: Build one lakh step by step from groups learners know, such as hundreds and thousands, and anchor it with familiar benchmarks.
Chapter 1
How Big Is One Lakh Compared with Everyday Quantities?
3:05
How Big Is One Lakh Compared with Everyday Quantities?
You'll learn: Compare one lakh with everyday quantities to feel how big it really is.
Indian and American/International systems
3 videos
Chapter 1
Read Indian Number Names from Lakh to Arab
3:03
Read Indian Number Names from Lakh to Arab
You'll learn: Indian commas group digits as thousands, then lakhs, crores and arabs every two places.
Chapter 1
Read Million and Billion in the American or International System
3:01
Read Million and Billion in the American or International System
You'll learn: International commas group digits in threes: thousands, millions and billions.
Chapter 1
Match Indian and International Names for the Same Number
3:02
Place value through button presses
2 videos
Chapter 1
Make the Same Number with Different Button Presses
3:29
Make the Same Number with Different Button Presses
You'll learn: The same number can be made with different combinations of +1, +10, +100 … presses by regrouping tens.
Chapter 1
Why Do the Fewest Clicks Equal the Digit Sum on Place-Value Buttons?
3:16
Why Do the Fewest Clicks Equal the Digit Sum on Place-Value Buttons?
You'll learn: With place-value buttons, the fewest presses use each digit as a count of its button, so the minimum equals the digit sum.
Exact and approximate values
2 videos
Chapter 1
When Do We Need an Exact Number?
3:13
When Do We Need an Exact Number?
You'll learn: Some situations need an exact number and others only a sensible approximation; the purpose decides.
Chapter 1
Use Nearest Place-Value Neighbours to Round a Number
3:19
Use Nearest Place-Value Neighbours to Round a Number
You'll learn: Round by finding the nearest place-value neighbours and choosing the closer one.
Estimating and comparing quantities
2 videos
Chapter 1
Estimate a Population Change with Sums and Differences
3:19
Estimate a Population Change with Sums and Differences
You'll learn: Estimate sums and differences of large numbers to judge a change such as population growth.
Chapter 1
Compare Large Quantities Using How Many Times
3:12
Compare Large Quantities Using How Many Times
You'll learn: Compare large quantities by asking 'how many times as much?', not only 'how much more?'.
Multiplication shortcuts
2 videos
Chapter 1
Multiply by 5, 25 or 125 Using 10, 100 or 1000
3:10
Multiply by 5, 25 or 125 Using 10, 100 or 1000
You'll learn: 5 = 10 ÷ 2, 25 = 100 ÷ 4 and 125 = 1000 ÷ 8, so multiply by a power of ten and divide: one shortcut, three cases.
Chapter 1
Regroup Factors to Make a Large Product Easier
3:15
Regroup Factors to Make a Large Product Easier
You'll learn: Reorder and regroup factors so that pairs like 4 × 25 or 8 × 125 make a long product easy.
Predicting product length
2 videos
Chapter 1
What Patterns Appear in Repeated-Digit Products?
3:14
What Patterns Appear in Repeated-Digit Products?
You'll learn: Products of repeated-digit numbers such as 11 × 11 or 111 × 111 form patterns worth predicting.
Chapter 1
Predict a Product's Digit Count Using Smallest and Largest Cases
3:21
Predict a Product's Digit Count Using Smallest and Largest Cases
You'll learn: Bound a product between the smallest and largest numbers with the given digit counts to predict its number of digits.
Calculations revealing large-number facts
1 video
Chapter 1
What Does a Large Calculation Tell Us About a Real Quantity?
3:17
What Does a Large Calculation Tell Us About a Real Quantity?
You'll learn: Turn the result of a large calculation back into a real quantity with sensible units and judge its size.
Estimation thought-experiments
2 videos
Chapter 1
Could a Lakh Buses Hold a City's Population?
3:16
Could a Lakh Buses Hold a City's Population?
You'll learn: Use stated assumptions about bus capacity to estimate whether a lakh buses could carry a city's population.
Chapter 1
Could You Reach the Moon in Ten Years?
3:29
Could You Reach the Moon in Ten Years?
You'll learn: Estimate in stages, distance then speed then time, to test whether the Moon is reachable in ten years.
Toothpick-digit exploration
1 video
Chapter 1
Make the Largest and Smallest Numbers with Fixed Toothpicks
3:10
Make the Largest and Smallest Numbers with Fixed Toothpicks
You'll learn: Moving a fixed number of toothpicks changes digits; plan moves to make the largest and smallest numbers.
Match Indian and International Names for the Same Number
You'll learn: Read the same number in both systems and match the names, e.g. 10 lakh = 1 million.