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 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 |
|---|---|---|---|---|---|---|
| 163 | 310 | 0 | 163 | 0 | 1 | 0 |
| 310 | 163 | 1 | 147 | 1 | 0 | 1 |
| 163 | 147 | 1 | 16 | 0 | 1 | -1 |
| 147 | 16 | 9 | 3 | 1 | -1 | 10 |
| 16 | 3 | 5 | 1 | -1 | 10 | -51 |
| 3 | 1 | 3 | 0 | 10 | -51 | 163 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 877 | 290 | 3 | 7 | 0 | 1 | -3 |
| 290 | 7 | 41 | 3 | 1 | -3 | 124 |
| 7 | 3 | 2 | 1 | -3 | 124 | -251 |
| 3 | 1 | 3 | 0 | 124 | -251 | 877 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 663 | 733 | 0 | 663 | 0 | 1 | 0 |
| 733 | 663 | 1 | 70 | 1 | 0 | 1 |
| 663 | 70 | 9 | 33 | 0 | 1 | -9 |
| 70 | 33 | 2 | 4 | 1 | -9 | 19 |
| 33 | 4 | 8 | 1 | -9 | 19 | -161 |
| 4 | 1 | 4 | 0 | 19 | -161 | 663 |
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 ≡ 507 × 310-1 (mod 163) ≡ 507 × 112 (mod 163) ≡ 60 (mod 163)x ≡ 521 × 290-1 (mod 877) ≡ 521 × 626 (mod 877) ≡ 779 (mod 877)x ≡ 542 × 733-1 (mod 663) ≡ 542 × 502 (mod 663) ≡ 254 (mod 663)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 60 (mod 163)
x ≡ 779 (mod 877)
x ≡ 254 (mod 663)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 163 × 877 × 663 = 94776513 - We calculate the numbers M1 to M3
M1=M/m1=94776513/163=581451,M2=M/m2=94776513/877=108069,M3=M/m3=94776513/663=142951 - 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 -38 mod 163 ≡ 125n b q r t1 t2 t3 163 581451 0 163 0 1 0 581451 163 3567 30 1 0 1 163 30 5 13 0 1 -5 30 13 2 4 1 -5 11 13 4 3 1 -5 11 -38 4 1 4 0 11 -38 163
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -31 mod 877 ≡ 846n b q r t1 t2 t3 877 108069 0 877 0 1 0 108069 877 123 198 1 0 1 877 198 4 85 0 1 -4 198 85 2 28 1 -4 9 85 28 3 1 -4 9 -31 28 1 28 0 9 -31 877
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is 178 mod 663 ≡ 178n b q r t1 t2 t3 663 142951 0 663 0 1 0 142951 663 215 406 1 0 1 663 406 1 257 0 1 -1 406 257 1 149 1 -1 2 257 149 1 108 -1 2 -3 149 108 1 41 2 -3 5 108 41 2 26 -3 5 -13 41 26 1 15 5 -13 18 26 15 1 11 -13 18 -31 15 11 1 4 18 -31 49 11 4 2 3 -31 49 -129 4 3 1 1 49 -129 178 3 1 3 0 -129 178 -663
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
= (60 × 581451 × 125 +
779 × 108069 × 846 +
254 × 142951 × 178) mod 94776513
= 63444713 (mod 94776513)
So our answer is 63444713 (mod 94776513).
Verification
So we found that x ≡ 63444713
If this is correct, then the following statements (i.e. the original equations) are true:
310x (mod 163) ≡ 507 (mod 163)
290x (mod 877) ≡ 521 (mod 877)
733x (mod 663) ≡ 542 (mod 663)
Let's see whether that's indeed the case if we use x ≡ 63444713.