That is quite a jump in numbers.
What you need are systems that allow you to cover the class, so for example having a colour card system of red, yellow and green which pupils can use to indicate when they feel they need help. They put the green card showing if they know what they should be doing and are happy, the red card if they don't know what to do or how to start. You at a glance can then see who needs help and who does not. Yellow means they think they know but might need some help. You can then prioritise who gets the help first reds, followed by yellows with a check on greens when the rest are sorted. Not ideal, but at least it would help you prioritise.