Explanation

If the sum of all digits of a number is divisible by 3, then the number itself is divisible by 3.

This is a divisibility rule for 3.

Explanation

Every real number is either a rational or irrational number: True. A real number can either be expressed as a fraction (rational) or cannot (irrational).

Every whole number is a natural number: False. Whole numbers include 0, but natural numbers start from 1. Therefore, 0 is a whole number but not a natural number.

All natural numbers are integers: True. Natural numbers are a subset of integers.

All integers are rational numbers: True. Every integer can be written as a fraction (e.g., 

5 = 5/1), so all integers are rational.

Explanation

To determine the quadrant, let's convert the angle to degrees:

8π/5 radians = (8 * 180°) / 5

= 288°

Since 288° lies between 270° and 360° (or -90° and 0° if considering the unit circle in a different manner), it falls in the:

4th quadrant

Explanation

In the 3rd quadrant, both the x and y coordinates are negative.

The point (-1, 2) has a positive y-coordinate, so it does not lie in the 3rd quadrant.

Explanation

A number is divisible by 8 if its last three digits form a number that is exactly divisible by 8.

For example, 4,320 is divisible by 8 because 320 ÷ 8 = 40 (a whole number).

Explanation

The harmonic mean is the reciprocal of the arithmetic mean of the reciprocals of the data points.

It is calculated as the inverse of the average of the inverses of the values.

Explanation

Explanation

1,5,9,13, ---- 40th

d=5-1=4 d=9-5=4 =1+(40-1)*4 =1+156 =157

U have to use the formula S=n/2 [2a+(n-1)d]

S=40/2[2(1)+(40-1)4]

S=20[2+(39)4]

S=20[156]

S=3160

ND-8-08-2023

Explanation

The multiplicative inverse of a number is its reciprocal.

For -1/9, the reciprocal is -9/1 or simply -9.

Explanation

A number divisible by both 2 and 5 is automatically divisible by their LCM = 10.

For example, 20 ÷ 2 = 10, 20 ÷ 5 = 4, and 20 ÷ 10 = 2.