How many significant figures ?

0.002300

  4

Step-by-step explanation:

Trailing zeros in a number with a decimal point are always considered to be significant. Leading zeros are not significant.

The significant digits are in bold. There are 4 of them.

  0.002300

452,489 to the nearest thousand is 452,000

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)