Just about everything I write has an estimation – however, I will just list ones that have significant estimations.

• Suppose you wanted to make a radioactive banana powered generator.  How big would it be?
• How big would a solar powered drone need to be?
• Could you fix Atlanta’s broken freeway by making a ramp so that cars could jump the gap?
• How much power does it take to fly this real life Iron Man suit?
• What is the power needed for this giant skyscraper waterfall?
• Could the Tesla electric truck be solar powered?
• How fast was this shark moving when it jumped out of the water?
• How long would it take to reach the top of a mountain using a human-powered chairlift?
• How much energy would it take to move 1 meter depth of water to the top of he Antartica ice sheet?
• Does a solar eclipse change the Earth’s temperature?
• How many different songs can there be?
• How far back in time do you have to go such that my number of ancestors is equal to the human population?
• How much oil can we get from the Earth and how long will it last?
• How big of a battery would you need to run your house?
• Which is worth more, a penny or a single potato chip?
• Could you charge your smart watch by shaking it?
• How long would it take for the whole world to do the ice bucket challenge?
• How much cement has China used?
• If you filled this arena with water, how long would it take to drink?
• How many batteries would you need to cook a turkey?
• How far could this drug shooting cannon shoot?
• What if everyone jumped in a lake?
• How many leaves are on this tree?
• How much does it cost to power your Christmas lights?
• How much rain does the Mississippi river need to flow?
• How difficult is the human powered helicopter?
• Could you jump off a building (and survive) by using bubble wrap?
• Can bird poop crack a windshield?
• How big would a stack of 1 trillion dollars be?
• Could you charge your phone with sound?
• How much time does an airbag have between crash and deployment? 
• How long would it take for one human to dig out this underground pool?