Math Help – Book 4 and Support Options

Hi I tried to post in my old entry about this topic but it prompted me to create a new one.  We have been using Arithmetic 4 as a guiding resource to my son’s modified Math curriculum.  My son has a tutor who uses mostly Math with Confidence and some Key to Fractions with topics that have been pre-selected by his SN teacher.  In the meantime, I do primarily the Arithmetic 4 with him with some Math games and enrichment activities together with art/movement etc.  I noticed with the big topics like for instance, Long Multiplication, things here can get very sticky and potentially frustrating.  Although I would say there is some progress, we were advised to use calculator to address overwhelm issues.  So far, I have told my son that he can use the calculator in the column addition but I would want him to work on the multiplication and lining up the numbers as per usual.  What is your suggestion or approach in handling these big topics?  Do we just plough through them or just make the adaptations to move forward?  I will assume this will also be a sticky case once we get to long division.  Just wanted to get a big picture sense of things as we are set to wrap up the school year and plan for the next.  Would Book 5 be already in the horizon given our pace?  I have delayed the Geometry because of this as my son did (Waldorf) Freehand Geometry last year.   Thanking everyone in advance and have a great Easter weekend!