Mathlingo is a fun early learning game for preschool toddlers & kindergarten kids to get a head start on counting, addition, subtraction, shapes &Solve Now
The mental math problems application includes child friendly interface and amazing graphics with the content that is suitable to teach and learn mental math for kids.
Actually, also has relevant ads, but other than that, detailed explaination too. Even the free version of this is good, excellent free app. Highly recommended! Whatever you calculate, it provides accurate solutions with answers.
Also, it provides step by step solutions with instructions and most importantly, accurate solutions, although sometimes it wont open on the app button so I have to search up the website for it but despite this little hiccup its amazing. Amazing what do i even say I'm speechless a must download for ur phone and u don't even need to buy premium bcs it makes it that easy for u.
After showing you the answer it even tells you the steps it has gone through to get to the answer, for free, but if you want to understand why it has chosen to do that you gotta buy the premium form, apart from that everything is great.