- #1

blumfeld0

- 148

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I was thinking there are 50,000 odd numbers less than 100,000 but how many of those start with an even number?

thanks

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- Thread starter blumfeld0
- Start date

- #1

blumfeld0

- 148

- 0

I was thinking there are 50,000 odd numbers less than 100,000 but how many of those start with an even number?

thanks

- #2

Diffy

- 441

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- #3

aquariss

- 2

- 0

I was thinking there are 50,000 odd numbers less than 100,000 but how many of those start with an even number?

thanks

not sure if you have learned how to use AP to tackle this qns.

2 4 6 8

For numbers starting with 2, we have 2, (20-29) , (200-299), (2000-2999), (20000-29999)

same for 4 6 and 8

For odd # starting with 2 :

For 2,

0

For 20-29,

1st odd term is 21 , d is 2, last term is 29

Tn = a + (n -1 )d

29 = 21 + (n-1)2

n = 5

For 200 to 299,

1st odd term is 201 , d is 2, last term is 299

Tn = a + (n -1 )d

299 = 201 + (n-1)2

n = 50

For 2000 to 2999,

1st odd term is 2001 , d is 2, last term is 2999

Tn = a + (n -1 )d

2999 = 2001 + (n-1)2

n = 500

For 20000 to 29999,

1st odd term is 20001 , d is 2, last term is 29999

Tn = a + (n -1 )d

29999 = 20001 + (n-1)2

n = 5000

Total # of terms = 4 x (5 + 50 + 500 + 5000) = 22220

I hope this will be of some help

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