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 |
|---|---|---|---|---|---|---|
| 959 | 505 | 1 | 454 | 0 | 1 | -1 |
| 505 | 454 | 1 | 51 | 1 | -1 | 2 |
| 454 | 51 | 8 | 46 | -1 | 2 | -17 |
| 51 | 46 | 1 | 5 | 2 | -17 | 19 |
| 46 | 5 | 9 | 1 | -17 | 19 | -188 |
| 5 | 1 | 5 | 0 | 19 | -188 | 959 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 948 | 341 | 2 | 266 | 0 | 1 | -2 |
| 341 | 266 | 1 | 75 | 1 | -2 | 3 |
| 266 | 75 | 3 | 41 | -2 | 3 | -11 |
| 75 | 41 | 1 | 34 | 3 | -11 | 14 |
| 41 | 34 | 1 | 7 | -11 | 14 | -25 |
| 34 | 7 | 4 | 6 | 14 | -25 | 114 |
| 7 | 6 | 1 | 1 | -25 | 114 | -139 |
| 6 | 1 | 6 | 0 | 114 | -139 | 948 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 755 | 593 | 1 | 162 | 0 | 1 | -1 |
| 593 | 162 | 3 | 107 | 1 | -1 | 4 |
| 162 | 107 | 1 | 55 | -1 | 4 | -5 |
| 107 | 55 | 1 | 52 | 4 | -5 | 9 |
| 55 | 52 | 1 | 3 | -5 | 9 | -14 |
| 52 | 3 | 17 | 1 | 9 | -14 | 247 |
| 3 | 1 | 3 | 0 | -14 | 247 | -755 |
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 ≡ 893 × 505-1 (mod 959) ≡ 893 × 771 (mod 959) ≡ 900 (mod 959)x ≡ 835 × 341-1 (mod 948) ≡ 835 × 809 (mod 948) ≡ 539 (mod 948)x ≡ 715 × 593-1 (mod 755) ≡ 715 × 247 (mod 755) ≡ 690 (mod 755)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 900 (mod 959)
x ≡ 539 (mod 948)
x ≡ 690 (mod 755)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 959 × 948 × 755 = 686394660 - We calculate the numbers M1 to M3
M1=M/m1=686394660/959=715740,M2=M/m2=686394660/948=724045,M3=M/m3=686394660/755=909132 - 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 303 mod 959 ≡ 303n b q r t1 t2 t3 959 715740 0 959 0 1 0 715740 959 746 326 1 0 1 959 326 2 307 0 1 -2 326 307 1 19 1 -2 3 307 19 16 3 -2 3 -50 19 3 6 1 3 -50 303 3 1 3 0 -50 303 -959
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -71 mod 948 ≡ 877n b q r t1 t2 t3 948 724045 0 948 0 1 0 724045 948 763 721 1 0 1 948 721 1 227 0 1 -1 721 227 3 40 1 -1 4 227 40 5 27 -1 4 -21 40 27 1 13 4 -21 25 27 13 2 1 -21 25 -71 13 1 13 0 25 -71 948
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -182 mod 755 ≡ 573n b q r t1 t2 t3 755 909132 0 755 0 1 0 909132 755 1204 112 1 0 1 755 112 6 83 0 1 -6 112 83 1 29 1 -6 7 83 29 2 25 -6 7 -20 29 25 1 4 7 -20 27 25 4 6 1 -20 27 -182 4 1 4 0 27 -182 755
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
= (900 × 715740 × 303 +
539 × 724045 × 877 +
690 × 909132 × 573) mod 686394660
= 452634515 (mod 686394660)
So our answer is 452634515 (mod 686394660).
Verification
So we found that x ≡ 452634515
If this is correct, then the following statements (i.e. the original equations) are true:
505x (mod 959) ≡ 893 (mod 959)
341x (mod 948) ≡ 835 (mod 948)
593x (mod 755) ≡ 715 (mod 755)
Let's see whether that's indeed the case if we use x ≡ 452634515.