Question

how many 4 digit numbers are divisible by 3,12,18​

Answer 1

Step-by-step explanation:

⇒  5=1×5=5

⇒  12=2×2×3=22×3

⇒  18=2×3×3=2×32

⇒  L.C.M of 5, 12 and 18  = 22×32×5=180

⇒  So our four digit number must be divisible by 180.

⇒  Smallest four digit number = 1000

⇒  So, 1801000=5.55≈6

⇒  Smallest four digit number that is divisible by 180 = 180×6=1080

⇒  We know highest four digit number = 9999

⇒  So, 1809999=55.55≈55

∴   Highest four digit number that is divisible by 180 = 180×55=9900

⇒  So, 1080,1260,....9900 is an AP.

⇒  Here, a1=1080,d=180,an=9900

∴   an=a1+(n−1)d

∴   9900=1080+(n−1)180

∴   9900=1080+180

Answer 2

Answer:

31.218

Step-by-step explanation:

i hope its helpful