Please-help-me-solve-this-question-How-many-4-digits-number-with-all-digits-different-are-tbere-between-1000-and-9999-such-tbat-the-difference-between-the-first-and-the-last-digit-is-plus-or-ninus-3

Question Number 49930 by OTCHRRE ABDULLAI last updated on 12/Dec/18

P l e a s e h e l p m e s o l v e t h i s q u e s t i o n

H o w m a n y 4 d i g i t s n u m b e r w i t h a l l d i g i t s

d i f f e r e n t a r e t b e r e b e t w e e n 1000 a n d 9999

s u c h t b a t t h e d i f f e r e n c e b e t w e e n t h e f i r s t

a n d t h e l a s t d i g i t i s p l u s o r n i n u s 3 .

Answered by mr W last updated on 12/Dec/18

n u m b e r p a i r s w i t h d i f f e r e n c e 3 :

0 / 3, 1 / 4, 2 / 5, \dots, 6 / 9 \Rightarrow 7 p a i r s

(2 \times 7 - 1) \times 8 \times 7 = 13 \times 8 \times 7 = 728

\Rightarrow 728 s u c h n u m b e r s .

- 1 b e c a u s e n u m b e r s s t a r t i n g w i t h 0

m u s t b e r e m o v e d .

Commented by OTCHRRE ABDULLAI last updated on 12/Dec/18

G o d r i c h l y b l e s s y o u M r . w f o r y o u r

h e l p a m m u c h g r e a t f u l

Commented by mr W last updated on 12/Dec/18

t h a n k y o u s i r!

Facebook Tweet Pin