Ii will award
how many numbers are written from n to k, including n and k?
how many natural numbers are there from 50 to 100? from 0 to 20?

k-n+1

51

21

Step-by-step explanation:

How many numbers are written from n to k

Lets look at a smaller example with real number

Lets go from 3 to 8

3 4 5 6 7 8

There are 6 numbers

We take 8 -3 = 5,  but we include the number 3 so we add it back in +1

5+1 =6

Lets look at a larger example

2 to 11

2,3,4,5,6,7,8,9,10,11

There are 10 numbers

11-2 =9  but we have to add back in the first number

9+1 =10

Now we are going from n to k

k-n = k-n, but we have to add back in the first number

k-n+1

How many numbers from 50 to 100

100-50 +1 = 51

How many numbers from 0 to 20

20-0+1 =21