Soluzione - Long subtraction
Spiegazione passo passo
1. Rewrite the numbers from top to bottom, aligned by their place values
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
2. Subtract the numbers using long subtraction method
Because the upper digit (1) in the ones column is too small to get a positive difference, borrow 1 from the digit (2) in the next number place which becomes (1) and get (11).
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
Subtract the numbers in the ones column from the top number:
11-2=9
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 9 |
Subtract the numbers in the tens column from the top number:
1-1=0
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 0 | 9 |
Because the upper digit (3) in the hundreds column is too small to get a positive difference, borrow 1 from the digit (4) in the next number place which becomes (3) and get (13).
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 0 | 9 |
Subtract the numbers in the hundreds column from the top number:
13-6=7
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 7 | 0 | 9 |
Because the upper digit (3) in the thousands column is too small to get a positive difference, borrow 1 from the digit (5) in the next number place which becomes (4) and get (13).
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 7 | 0 | 9 |
Subtract the numbers in the thousands column from the top number:
13-5=8
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 8 | 7 | 0 | 9 |
Subtract the numbers in the ten thousands column from the top number:
4-4=0
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 0 | 8 | 7 | 0 | 9 |
Because the upper digit (6) in the hundred thousands column is too small to get a positive difference, borrow 1 from the digit (7) in the next number place which becomes (6) and get (16).
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 6 | 16 | ||||||||
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 0 | 8 | 7 | 0 | 9 |
Subtract the numbers in the hundred thousands column from the top number:
16-9=7
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 6 | 16 | ||||||||
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 7 | 0 | 8 | 7 | 0 | 9 |
Because the upper digit (6) in the millions column is too small to get a positive difference, borrow 1 from the digit (8) in the next number place which becomes (7) and get (16).
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 7 | 16 | ||||||||
| 6 | 16 | ||||||||
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 7 | 0 | 8 | 7 | 0 | 9 |
Subtract the numbers in the millions column from the top number:
16-8=8
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 7 | 16 | ||||||||
| 6 | 16 | ||||||||
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 8 | 7 | 0 | 8 | 7 | 0 | 9 |
Subtract the numbers in the ten millions column from the top number:
7-7=0
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 7 | 16 | ||||||||
| 6 | 16 | ||||||||
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 0 | 8 | 7 | 0 | 8 | 7 | 0 | 9 |
Write 9 in the hundred millions place.
| Place value | hundred millions | ten millions | millions | hundred thousands | ten thousands | thousands | hundreds | tens | ones |
| 7 | 16 | ||||||||
| 6 | 16 | ||||||||
| 4 | 13 | ||||||||
| 3 | 13 | ||||||||
| 1 | 11 | ||||||||
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| - | 7 | 8 | 9 | 4 | 5 | 6 | 1 | 2 | |
| 9 | 0 | 8 | 7 | 0 | 8 | 7 | 0 | 9 |
The solution is: 908,708,709
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