Explanation

Look at the pattern:

1 + 2 = 5  

1 square + 2 square = 1 + 4 = 5

2 + 3 = 13  

2 square + 3 square = 4 + 9 = 13

3 + 4 = 25  

3 square + 4 square = 9 + 16 = 25

So the rule is: a + b = a square + b square

Now find 4 + 5  

4 square + 5 square = 16 + 25 = 41

Last updated 07 Nov 2026 by NA

Explanation

The prime numbers between 60 and 80 are:

61, 67, 71, 73, and 79

Let's add them up:

61 + 67 = 128

128 + 71 = 199

199 + 73 = 272

272 + 79 = 351

Last updated by NA on 05-11-2026

Explanation

Sum:

2+3+5+7+11+13+17+19=77

Correct Answer: 77

• Prime numbers are divisible only by 1 and themselves.

• 1 is not a prime number.

  
  

  Last updated by NA on 04-11-2026

Explanation

120 men can do work = 30 days

1 man can do this work = 120 x 30 = 3600 days

80 men can do this work = 3600/80 = 45 days

Last updated by NA on 04-11-2026

Explanation

The prime numbers less than 25 are: 2, 3, 5, 7, 11, 13, 17, 19, and 23.

Let's add them up:

2 + 3 = 5

5 + 5 = 10

10 + 7 = 17

17 + 11 = 28

28 + 13 = 41

41 + 17 = 58

58 + 19 = 77

77 + 23 = 100

So, the sum of prime numbers less than 25 is: 100

Last updated by NA on 04-11-2026