7 digits.
Nine million of them.
9*106 or 9 million.
Terence Tao's 10 million digit prime number
2827163 to the nearest million is 3 million. The millions digit is 2. The next digit is 8; this is 5 or more, so add one to the millions digit Replace all digits to the right of the millions digit with 0s. 2827163 ⇒ 3000000 = 3 million
1 million = 1,000,000 → 17914351 = 17914351 ÷ 1,000,000 million = 17.914351 million To the nearest tenth of a million this is rounded using the hundredth of a million to decide whether to round up or down. The hundredth of a million digit is 1, so sound down → 17.914351 million → 17.9 million to the nearest tenth of a million → 17.9 million = 17.9 × 1,000,000 = 17,900,000 Alternatively: Tenth of a million = 1/10 × 1,000,000 = 100,000 → Rounding to the nearest tenth of a million is rounding to the nearest 100,000 (hundred thousand) The hundred thousand digit is the 6th digit from the right hand end (of a whole number), so the ten thousand digit (the 5th digit from the right hand end) is the deciding digit. Round the 6th digit based on the 5th digit and then replace all the digits to the right of the 6th digit by zeros. The 5th from the end is '1', so round down → 17914351 → 17900000 to the nearest tenth of a million.
well the first 9 digit number is 100 million 100,000,000 the last 9 digit number is 999 million 999,999,999 just minus the two numbers and you get... 899,999,999 so there are around 900 million 9 digit numbers.
In order to answer that question, we need to know the average weight of a digit.
One of them.
3,500,000 = 3.5 million
7
20,000,000