Consecutive Numbers
Part of the Fundamentals section of Coddy's Algebra journey. Lesson 52 of 64.
"Two consecutive whole numbers add up to 25. What are they?" Consecutive means one after the other. If the first number is n, the next one is n + 1. Their sum is 25:
n + (n + 1) = 25
Collect the like terms to get 2n + 1 = 25. Subtract 1 from both sides, then divide by 2, and you get n = 12. The numbers are 12 and 13. Check that 12 + 13 = 25.
Consecutive even numbers differ by 2, and so do consecutive odd numbers. Write them as n and n + 2. Write every quantity in the problem in terms of the same unknown. Then use the relationship the problem gives to write one equation.
Challenge
MediumTwo consecutive numbers add up to 41, so n + (n + 1) = 41. Solve for n, the smaller number.
Try it yourself
Solve for n
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Fundamentals
1What an Equation Is
The EquationFinding the UnknownThe Same to Both SidesSolved Means AloneRecap: First Equations4Two-Step Equations
Two Layers to UndoSubtract, Then DivideAdd, Then DivideA Division InsideNegatives in Two StepsRecap: Two-Step Equations7Fractions in Equations
A Fraction CoefficientClearing One DenominatorTwo DenominatorsA Fraction Around a SumCross-MultiplyingRecap: Fractions10From Words to Equations
Phrases into ExpressionsSentences into EquationsConsecutive NumbersAge and MoneyA Perimeter ProblemRecap: Words2One-Step Equations
Undoing AdditionUndoing SubtractionUndoing MultiplicationUndoing DivisionInverse OperationsRecap: One-Step Equations5Tidying First
Like TermsTerms and Numbers MixedThe Distributive PropertyDistributing a SubtractionTidy, Then SolveRecap: Tidying First