Master cross-multiplication in just a few clicks with our interactive calculator
Looking for a quick, clear, and reliable way to solve your proportionality problems? Whether you need to calculate a price, a distance, an average speed, or fill in a proportion table, cross-multiplication is your ally. Use our calculator below and save valuable time.
Calculate a cross product instantly
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Understanding cross-multiplication: method, examples, and applications
Le cross product is an essential method for resolving situations of
proportionalityIt is based on a simple rule: if two ratios are equal,
So cross-multiplication is alsoThis is a technique used both in
mathematics than in everyday life.
The cross product formula
In one proportionality tableIf you have three known values ​​and one unknown,
Cross-multiplication makes it easy to find the fourth:
a / b = c / d ⟶ a × d = b × c
Then all that's needed is multiply by cross two known quantities, then of to divide by the last one to find the missing value.
Simple example
If 3 baguettes cost €1,50, how much do 5 baguettes cost?
| Number of baguettes | Price in € |
|---|---|
| 3 | 1,50 |
| 5 | x |
We apply the cross-multiplication: x = (5 × 1,50) / 3 = €2,50
When to use cross-multiplication?
Le cross product is useful in many situations:
- Fill in a proportionality table
- Calculate a proportional price
- Determine a distance traveled Ă constant speed
- Estimate a travel time or an average speed
- Solve equations of proportion (rule of three)
- Complete a proportional
- Represent a linear function graphically
- Apply a multiplier coefficient or a percentage
Either it's about proportional quantities (liters, kilos, movie tickets…) or situations
In complex mathematics, the rule applies simply and efficiently.
Why use our cross product calculator?
- Time Saving : no more mistakes mental calculation
- Guaranteed accuracy formula applied automatically
- Suitable for students, parents, teachers, professionals
- Compatible with : price, speed, percentages, quantities, etc.
Use interactive calculator at the top of the page to instantly find the
missing value. Whether in decimals, fractions or complex values, it adapts to all your needs.
Frequently Asked Questions about Cross Product
How do you perform a cross-multiplication?
We need to identify the two proportional relationships, then multiplier cross-shaped and to divide to find the unknown value.
What is the difference between cross-multiplication and the rule of three?
It's the same method! The rule of three is the common usage of cross product in practical situations.
Can I use this calculator for percentages?
Yes. It allows you to calculate a percentage, a Price including VAT, a discount, or a multiplier coefficient.
Does this calculation work for linear functions?
Absolutely. Cross-multiplication is the basis of everything. affine function ou linear function where the relationship is proportional.
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