Math practice for 13 year olds - page 267 of 413
Number of problems found: 8260
- Digit sum
How many are three-digit numbers that have a digit sum of 6? - Two rectangles
I cut out two rectangles with 54 cm² and 90 cm². Their sides are expressed in whole centimeters. If I put these rectangles together, I get a rectangle with an area of 144 cm². What dimensions can this large rectangle have? Write all options. Explain your - Tea Blend Mixture
A merchant sells a blend of two types of tea at 450 CZK per kilogram. One type costs 900 CZK/kg, and the cheaper type costs 369 CZK/kg. How much of each type is needed for 5 kg of the blend? - CuSO4 mixture
How many grams of solid CuSO₄ must be added to 450 g of a 15% CuSO₄ solution to produce a 25% solution? - The big clock
The hands of a clock stop at a random moment. What is the probability that: a) the hour hand shows a time between 1:00 and 3:00? b) the minute hand is in the same region as the hour hand as described in part a)? c) the clock shows a time between 21:00 and - Intersections
Find the intersections of the function plot with coordinate axes: f (x): y = x + 3/5 - Calculate
Calculate the surface of the cube if its volume is 64 cm³. - Outfit Combination Count
Milan found out that he could wear pants and a T-shirt in a total of 28 different ways. How many T-shirts and pants can he have? List all options. - Electricity consumption
Calculate how much we will pay for 1 hour of consumed electrical energy if the seller sets a price of 0.126 euros for 1 kWh (all appliances together for 1 hour of work). Table: Appliance ; Power (W) Washing machine ; 2300 W Bulb ; 40 W Refrigerator; 200 W - Glass with icecream
We have six kinds of ice cream and five kinds of fruit. If we put three cups of ice cream and two fruits into each glass, how many uniquely decorated glasses can there be? - Performance
Two masons with the same performance would have been made of plaster for six days. One of them, however, has increased its daily performance by 50%. How long would it take them now to make plaster together? - Board Length Combination Problem
Ujo Vilém needs a board 665 cm long. Without which boards cannot such a board be assembled? Find all options. 256 cm 114 cm 204 cm 198 cm 47 cm 87 cm - Bulbs and electricity
In the sports hall, 875 identical light bulbs are on for 2 hours. How long would 100 such light bulbs need to be on to consume the same amount of electricity? - Container volume percentage
By what percentage is the volume of the first container larger than the volume of the second when the first container has 70 liters and the second 36 liters? - Bicycle Wheel Rotations
How many times does a bicycle wheel with a 100 cm circumference turn on a 24 km long track? - Bank Deposit with Prize
The prize on the winning passbook with a deposit of CZK 12,390 was 15%. How much will be on the book after the prize is credited? - Summer camp
Eighty-four children spent their holidays at the summer camp. There were eight fewer boys than girls. What percentage were boys, and what percentage were girls? - Interior Exterior Angles Size
Calculate the sizes of the remaining inner and outer angles. Alpha with comma α '= 140 ° and beta with comma β' = 100 °. - Right Triangle Calculations
We know the right angle γ, side b = 14 cm, and height vc = 8.8 cm in the right triangle ABC. Calculate: angle α = angle β = side a = side c = - Angle of diagonal
The angle between the body diagonal of a regular quadrilateral and its base is 60°. The edge of the base has a length of 10 cm. Calculate the body volume.
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