Explanation:
we see 10 equal units or intervals on the main line.
after these 10 equal units we see the final value : 10¹².
so, each of these units or intervals must be worth
10¹²/10 = 10¹²/10¹ = 10¹¹.
and we get the intervals
0 to 1×10¹¹
1×10¹¹ to 2×10¹¹
2×10¹¹ to 3×10¹¹
...
9×10¹¹ to 10×10¹¹ (= 10¹²)
now, the interval 7×10¹¹ to 8×10¹¹ is refined into 10 equal intervals itself.
each one of these 10 subunits or intervals is now worth 10¹¹/10 = 10¹⁰.
and that means these intervals stand for
7×10¹¹ + 0×10¹⁰ to 7×10¹¹ + 1×10¹⁰
7×10¹¹ + 1×10¹⁰ to 7×10¹¹ + 2×10¹⁰
7×10¹¹ + 2×10¹⁰ to 7×10¹¹ + 3×10¹⁰
...
7×10¹¹ + 9×10¹⁰ to 7×10¹¹ + 10×10¹⁰ (= 10¹¹)
=
7×10¹¹ + 9×10¹⁰ to 7×10¹¹ + 1×10¹¹ = 8×10¹¹
therefore,
point A = 7×10¹¹ + 4×10¹⁰ = 7.4×10¹¹ = 740,000,000,000 =
= 740 billion