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Ministerio De Educacion: Reglas Graduadas
Three rules are given of the same length, but graduated in a different way. You will have to find out how many different distances you can measure, based on the marks that each one has.
National Institute of Educational Technologies and Teacher Training (Spain)
Ministerio De Educacion: El Sistema Decimal De Numeracion
Practice your knowledge of different number systems with the interactive example then check your knowledge with the different exercises.
National Institute of Educational Technologies and Teacher Training (Spain)
Ministerio De Educacion: Divisores Y Primos
Reinforce your knowledge on prime numbers and their divisors.