Step-by-step explanation:
every position in a number stands for a different power of 10, which is then multiplied by the digit in that position.
and the value of the whole number is the sum of these little individual calculations.
left of the decimal point we start with 10⁰ = 1 as basic value.
then the second position left of the decimal point stands for 10¹ = 10.
the third position left of the decimal point stands for 10² = 100.
and so on.
now, right of the decimal point we go in the other direction. the first position right of the decimal point stands for 10^-1 = 1/10.
the second position stands for 10^-2 = 1/100.
and so on.
so, the 7 in this number has the value of 7/10 or 7 tenths.
the given number would be fully written
3×10⁶ + 6×10⁵ + 8×10⁴ + 4×10³ + 5×10² + 9×10¹ + 1×10⁰ + 7×10^-1 + 4×10^-2
the decimal point tells us for a number where to begin counting with 10⁰ and 10^-1.
