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System Design Back of the Envelope > Untitled Deck > Flashcards

Untitled Deck Flashcards

1
Q
A
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2
Q

What is 1 Hundred in the Indian Number System?

A

1 Hundred (same in both systems)

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3
Q

What is 1 Thousand in the Indian Number System?

A

1 Thousand (same in both systems)

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4
Q

What is 1 Lakh in the International Number System?

A

100 Thousand (100,000)

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5
Q

What is 1 Million in Indian Number System?

A

10 Lakh or 0.1 Crore

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6
Q

What is 1 Crore in the International Number System?

A

10 Million (10,000,000)

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7
Q

What is 1 Billion in Indian terms?

A

100 Crore or 1 Arab

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8
Q

What is 1 Arab in the International Number System?

A

1 Billion (1,000,000,000)

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9
Q

What is 1 Trillion in Indian terms?

A

1 Lakh Crore or 1 Kharab

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10
Q

What is 1 Kharab in the International Number System?

A

1 Trillion (1,000,000,000,000)

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11
Q

What is 1 Quadrillion in Indian terms?

A

10 Lakh Kharab or 1 Neel

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12
Q

1 Crore is equal to how many Million?

A

10 Million

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13
Q

1 Million is equal to how many Crore?

A

0.1 Crore

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14
Q

5 Million is equal to how many Crore?

A

0.5 Crore

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15
Q

50 Million is equal to how many Crore?

A

5 Crore

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16
Q

100 Million is equal to how many Crore?

A

10 Crore

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17
Q

1 Billion is equal to how many Crore?

A

100 Crore

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18
Q

10 Crore is equal to how many Million?

A

100 Million

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19
Q

100 Crore is equal to what in the International System?

A

1 Billion

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20
Q

1000 Crore is equal to what in the International System?

A

10 Billion

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21
Q

1 Lakh Crore is equal to what in the International System?

A

1 Trillion

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22
Q

What is 10⁰ called?

A

One (1)

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23
Q

What is 10¹ called?

A

Ten (10)

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24
Q

What is 10² called?

A

Hundred (100)

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25
Q

What is 10³ called?

A

Thousand (1,000)

26
Q

What is 10⁴ called in the Indian System?

A

Ten Thousand (10,000)

27
Q

What is 10⁵ called in the Indian System?

A

Lakh (1,00,000)

28
Q

What is 10⁶ called in the International System?

A

Million (1,000,000)

29
Q

What is 10⁷ called in the Indian System?

A

Crore (1,00,00,000)

30
Q

What is 10⁹ called in the International System?

A

Billion (1,000,000,000)

31
Q

What is 10¹² called in the International System?

A

Trillion (1,000,000,000,000)

32
Q

What power of 10 is a Lakh?

33
Q

What power of 10 is a Crore?

34
Q

What power of 10 is a Million?

35
Q

What power of 10 is a Billion?

36
Q

What power of 10 is a Trillion?

37
Q

Quick hack: Million to Crore conversion formula?

A

Multiply Million by 0.1 to get Crore

38
Q

Quick hack: Crore to Million conversion formula?

A

Multiply Crore by 10 to get Million

39
Q

Memory trick: What’s the pattern in International Number System?

A

Every 3 zeros = new unit (Thousand, Million, Billion, Trillion)

40
Q

Memory trick: What’s the pattern in Indian Number System?

A

After thousand, every 2 zeros = new unit (Lakh, Crore)

41
Q

How to quickly calculate 1 Billion users making 5 requests per day?

A

5 Billion requests per day ≈ 60,000 requests per second (divide by 86,400 seconds in a day)

42
Q

Quick estimation: If 1 user takes 100KB of storage, how much is needed for 10 million users?

A

1 TB (10M × 100KB = 1,000B KB = 1,000 GB = 1 TB)

43
Q

Hack for percentage to decimal conversion?

A

Move decimal point two places left (25% = 0.25)

44
Q

Quick mental math: Double a number each time, starting with 1, what’s the 10th number?

A

2⁹ = 512 (1, 2, 4, 8, 16, 32, 64, 128, 256, 512)

45
Q

Quick approximation of 2¹⁰?

A

Approximately 1,000 (actual value: 1,024)

46
Q

Memory trick: Power of 2 sequence pattern?

A

2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096…

47
Q

How many Bytes in a Kilobyte (KB)?

A

1,024 Bytes = 1 KB (2¹⁰)

48
Q

How many KB in a Megabyte (MB)?

A

1,024 KB = 1 MB (2²⁰ bytes)

49
Q

How many MB in a Gigabyte (GB)?

A

1,024 MB = 1 GB (2³⁰ bytes)

50
Q

How many GB in a Terabyte (TB)?

A

1,024 GB = 1 TB (2⁴⁰ bytes)

51
Q

How many TB in a Petabyte (PB)?

A

1,024 TB = 1 PB (2⁵⁰ bytes)

52
Q

Quick approximation: 1 GB is approximately how many MB?

A

1,000 MB (actual: 1,024 MB)

53
Q

If a single HD movie is 4GB, how many movies can a 1TB drive hold?

A

Approximately 250 movies (1024 ÷ 4 = 256)

54
Q

If a text file with 1 page is about 2KB, how many pages in 1MB?

A

About 500 pages (1024 KB ÷ 2 KB = 512 pages)

55
Q

In system design, what’s the typical storage size of a small profile image?

56
Q

What is the approximate size of 1 million records with 1KB each?

A

1 GB (1M × 1KB = 1000M KB = 1000 GB = ~1 GB)

57
Q

A system with 1 million daily active users, each making 10 requests/day. Calculate QPS (Queries Per Second).

A

~116 QPS (1,000,000 × 10 ÷ 86,400)

58
Q

If each request generates 1KB of log data, how much storage is needed daily in the above system?

A

~10 GB per day (10M requests × 1KB)

59
Q

If a database can handle 1,000 QPS, how many users can it support if each user makes 20 requests/day?

A

~4.32 million users (1,000 × 86,400 ÷ 20)

60
Q

In a distributed system, if each node can handle 5,000 requests per second, how many nodes needed for 1 million QPS?

A

200 nodes (1,000,000 ÷ 5,000)

61
Q

If average response time is 100ms, and you need to handle 1,000 concurrent requests, calculate minimum threads needed.

A

100 threads (1,000 × 0.1)

System Design Back of the Envelope (1 decks)

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