Welcome to ChineseRemainderTheorem.com!
Use the calculator below to get a step-by-step calculation of the Chinese Remainder Theory. Just enter the numbers you would like and press "Calculate" .
This removes all numbers from the textboxes, such that you can fill in your own.
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This button is similar to the "Clear everything" button, but only clears the left column.
This is useful if you want your equations to be of the form x ≡ a (mod m) rather than bx ≡ a (mod m).
In that case, it can be especially useful after using the random numbers button.
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Are you ready to view a full step-by-step Chinese Remainder Theorem calculation for the numbers you have entered? Then use this button!
Want to know more?- Read about how to execute the Chinese Remainder Theorem
- Discover different ways to calculate multiplicative inverses
Transform the equations
You used one or more of the fields on the left, so your equations are of the form bx ≡ a mod m.
We want them to be of the form x ≡ a mod m, so we need to move the values on the left to the right side of the equation.
For a more detailed explanation about how this works, see this part of our page about how to execute the Chinese Remainder algorithm.
First, we calculate the inverses of the leftmost value on each row:
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 829 | 708 | 1 | 121 | 0 | 1 | -1 |
| 708 | 121 | 5 | 103 | 1 | -1 | 6 |
| 121 | 103 | 1 | 18 | -1 | 6 | -7 |
| 103 | 18 | 5 | 13 | 6 | -7 | 41 |
| 18 | 13 | 1 | 5 | -7 | 41 | -48 |
| 13 | 5 | 2 | 3 | 41 | -48 | 137 |
| 5 | 3 | 1 | 2 | -48 | 137 | -185 |
| 3 | 2 | 1 | 1 | 137 | -185 | 322 |
| 2 | 1 | 2 | 0 | -185 | 322 | -829 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 809 | 526 | 1 | 283 | 0 | 1 | -1 |
| 526 | 283 | 1 | 243 | 1 | -1 | 2 |
| 283 | 243 | 1 | 40 | -1 | 2 | -3 |
| 243 | 40 | 6 | 3 | 2 | -3 | 20 |
| 40 | 3 | 13 | 1 | -3 | 20 | -263 |
| 3 | 1 | 3 | 0 | 20 | -263 | 809 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 773 | 442 | 1 | 331 | 0 | 1 | -1 |
| 442 | 331 | 1 | 111 | 1 | -1 | 2 |
| 331 | 111 | 2 | 109 | -1 | 2 | -5 |
| 111 | 109 | 1 | 2 | 2 | -5 | 7 |
| 109 | 2 | 54 | 1 | -5 | 7 | -383 |
| 2 | 1 | 2 | 0 | 7 | -383 | 773 |
Source: ExtendedEuclideanAlgorithm.com
Click on any row to reveal a more detailed calculation of each multiplicative inverse.
Now that we now the inverses, let's move the leftmost value on each row to the right of the equation:
x ≡ 113 × 708-1 (mod 829) ≡ 113 × 322 (mod 829) ≡ 739 (mod 829)x ≡ 493 × 526-1 (mod 809) ≡ 493 × 546 (mod 809) ≡ 590 (mod 809)x ≡ 348 × 442-1 (mod 773) ≡ 348 × 390 (mod 773) ≡ 445 (mod 773)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 739 (mod 829)
x ≡ 590 (mod 809)
x ≡ 445 (mod 773)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 829 × 809 × 773 = 518420953 - We calculate the numbers M1 to M3
M1=M/m1=518420953/829=625357,M2=M/m2=518420953/809=640817,M3=M/m3=518420953/773=670661 - We now calculate the modular multiplicative inverses M1-1 to M3-1
Have a look at the page that explains how to calculate modular multiplicative inverse.
Using, for example, the Extended Euclidean Algorithm, we will find that:
So our multiplicative inverse is 245 mod 829 ≡ 245n b q r t1 t2 t3 829 625357 0 829 0 1 0 625357 829 754 291 1 0 1 829 291 2 247 0 1 -2 291 247 1 44 1 -2 3 247 44 5 27 -2 3 -17 44 27 1 17 3 -17 20 27 17 1 10 -17 20 -37 17 10 1 7 20 -37 57 10 7 1 3 -37 57 -94 7 3 2 1 57 -94 245 3 1 3 0 -94 245 -829
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is 100 mod 809 ≡ 100n b q r t1 t2 t3 809 640817 0 809 0 1 0 640817 809 792 89 1 0 1 809 89 9 8 0 1 -9 89 8 11 1 1 -9 100 8 1 8 0 -9 100 -809
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -324 mod 773 ≡ 449n b q r t1 t2 t3 773 670661 0 773 0 1 0 670661 773 867 470 1 0 1 773 470 1 303 0 1 -1 470 303 1 167 1 -1 2 303 167 1 136 -1 2 -3 167 136 1 31 2 -3 5 136 31 4 12 -3 5 -23 31 12 2 7 5 -23 51 12 7 1 5 -23 51 -74 7 5 1 2 51 -74 125 5 2 2 1 -74 125 -324 2 1 2 0 125 -324 773
Source: ExtendedEuclideanAlgorithm.com
- Now we can calculate x with the equation we saw earlier
x = (a1 × M1 × M1-1 + a2 × M2 × M2-1 + ... + ak × Mk × Mk-1) mod M
= (739 × 625357 × 245 +
590 × 640817 × 100 +
445 × 670661 × 449) mod 518420953
= 420532543 (mod 518420953)
So our answer is 420532543 (mod 518420953).
Verification
So we found that x ≡ 420532543
If this is correct, then the following statements (i.e. the original equations) are true:
708x (mod 829) ≡ 113 (mod 829)
526x (mod 809) ≡ 493 (mod 809)
442x (mod 773) ≡ 348 (mod 773)
Let's see whether that's indeed the case if we use x ≡ 420532543.